Rock Hill High School
Honors Biology 1

Updated Monday, April 07, 2014


Hit Counter

 IndexHome   Introduction BiochemistryCellsCell EnergyHeredityEvolutionEcology

TextbookCalendarCreate-a-GraphExpDesRefGuideRHHSStudent ResourcesStandards

Click Here For Genetics Problems



DNA Structure


How DNA is put together


› Notes from Class:
DNA History, Structure, Packaging PPT

› Links:
DNA: The history of its discovery
DNA Structure: animated (John Kyrk)
~DNA Models (yes, they're movable)
DNA Packaging animation


  DNA History 193-195
  DNA Structure 196-199




Double helix, sugar-phosphate, backbone, adenine, guanine, cytosine, thymine, purine, pyrimidine' hydrogen bond' complementary bases





DNA Replication

Making new DNA during Synthesis stage

DNA Replication johnkyrk
DNA Replication McGrawHill
DNA Replication bioteach
DNA Replication stolaf (Meselson-Stahl Experiment)
DNA Replication semiconservatism
DNA Replication HHMI
   (This is the best: how it really goes down)



   DNA Replication 200-202



DNA Polymerase III
DNA Polymerase I
RNA Primase
RNA Primer
leading strand
lagging strand
Okazaki fragments
5' / 3'
parent strand
new strand
replication bubble
replication fork



Protein Synthesis

Making proteins during G phase


How does a blueprint of a house become a house?  How does this "code" in a nucleus become flesh and blood???  Here's how...

Proteins run everything (see some below). This is when RNA plays its role with DNA to help produce proteins, a process called protein synthesis, which include the processes of Transcription and Translation.

Here's a difference between DNA and RNA: its sugar...


 DNA --> transcription --> RNA --> translation --> PROTEIN

› Protein Synthesis:
   A step-by-step guide through transcription and translation

› RNA / Protein Synthesis Power Point

› Protein Synthesis animations:

  Wiley Biology Basics
   Transcription and Translation (HHMI)

DNA transcription (basic detail)
Translation (advanced detail)
  Protein Synthesis Transcription/Translation Movie  
Transcription/Translation Narrated

 › Human Genome Project

 › Protein Data Bank (





RNA Polymerase
amino acids





How gametes
are formed




Click on these images of Meiosis I and II to see enlarged version. (source)


   › Meiosis Power Point (from class)

   › Meiosis Cutout-Matching Activity

   › Nondisjunction Disorders (ppt)

   › Meiosis Study Sheet

 › Chromosome Structure (John Kyrk)
Meiosis Animation 1
Meiosis Animation (Narrated)
   Meiosis Self - Tutorial  If you get this, you've GOT it.

   Practice matching a karyotype

   Karyotype Activity:
What is your condition's name (if it has one)? 
     How survivable is it? 
     What are the symptoms of this condition?

     Use these sites for your research:

Cytogenetics Lab (karyotyping)
Genetic Disorders
          Learning Genetic Disorders

When the age of a mother-to-be gets around 40 or older, notice the probability that Down Syndrome (and other anomalies) will likely occur with her baby:
image source)





 Chromosome Structure:
 Meiosis: 161-165




sex chromosomes
homologous chromosomes
diploid / haploid
somatic / gametes
2n / n
sister chromatids
non-sister chromatids
crossing over
polar bodies

Stages of Meiosis Animation:


Meiosis/Mitosis Animation:


 Go here, then click "What is Heredity?"





When gametes combine



 Flipped Classroom:
Use these videos below to help you learn concepts about genetics on your own.


 Mendelian Genetics


 Beginners guide to Punnett squares

 Pedigree problems

 Solving Hardy-Weinberg problems

Video: How to do a Dihybrid cross

Click Here For Genetics Problems

TEST ON WEDNESDAY, April 9 (Late start day)
Study guide on Google Calendar

 › Lesson 1  Complete Dominance ppt
› Lesson 2 Incomplete/Codominance ppt
› Lesson 3 Mutations, Sex-linked traits, Disorders ppt
› Lesson 4 Modifying Genes ppt

 › Practice Genetics Problems (click here)

› GENE THERAPY / CLONING   pros and cons

› Punnett Square Practice (monohybrids)

› WebLab  Cross two dragons

› Genetics Lab Directory
   Cross lemmings, chickens, etc.... see what you come up with.

› Blood typing interactive game 



› Mutagens: The result of too much radiation (Chernobyl)
Chernobyl ppt.
   Chernobyl Pictorial Show
   See what happens when the mutagen radiation is released into the environment. 
   For humans, people's DNA replication are harmfully altered... in their body cells
   as well as their gametes.  This results in deformed bodies and minds,
   even in the womb...

    (when the web site loads, click the play button > )


Article 1:
The Father of Modern Genetics: Gregor Mendel

Gregor Mendel's work led to major contributions to the understanding of how heritable traits are passed between generations.  From his work, two major principles were established that we still operate by:

1. Law (Principle) of Segregation (one allele from each parent)
Explains how alleles are separated during meiosis.
   a. Each gamete receives one of the two alleles that the parent carries for each trait. Each gamete has the same chance of receiving either one of the allele for each trait.)
During fertilization (when sperm and egg unite), each parent organism donates one copy of each gene to the offspring.

2. Law (Principle) of Independent Assortment 
tates that the segregation of the alleles of one trait does not affect the segregation of the alleles of another trait.  Remember Metaphase I and Metaphase II; which chromosomes are pulled which direction is purely by chance.
     a. Genes on separate chromosomes separate independently during meiosis.
     b. This law holds true for all genes unless the genes are
linked. In this case, these genes do not independently segregate during gamete formation, usually because they
are in close proximity on the same chromosome.



Article 2:
The ABO Blood Typing System

There are more than 20 genetically determined blood group systems known today, but the ABO and Rh systems are the most important ones used for blood transfusions. 

The ABO blood group was discovered in 1900-01
at the University of Vienna by an Austrian named Karl Landsteiner.  He wanted to know why some people benefited greatly from receiving a blood transfusion from someone else, while others seemed to die from it…

How the human body’s immune system works: 

Antigens: a molecule on a cell surface that elicits an immune response (white blood cells attacking the perceived foreign cell containing the antigen).  The antigen of interest found on blood cells is two carbohydrates (A and B) that may be found on blood cell surfaces.

Antibody: a protein your white blood cells produce to attach to antigens and attempt to counter their effect. You may have antibodies in you that are seeking out antigen A or B.
If successful, the antibodies can cause blood clumping (agglutination). The agglutinated red cells can clog blood vessels and stop the circulation of the blood to various parts of the body. They also crack and its contents leak out in the body. The red blood cells contain hemoglobin, which becomes toxic when outside the cell. This can have fatal consequences for the patient.


Article 3:
Hemolitic anemia (Rh Disease)

Hypermunes Vaccine Visual AidRh blood types were discovered in 1940 by Karl Landsteiner and Alexander Wiener.  The Rh system was named after rhesus monkeys, since they were initially used in the research to make the antiserum for typing blood samples.  If the antiserum agglutinates your red cells, you are Rh+.  If it doesn't, you are Rh-. People are either Rh- or Rh+.  Those who are Rh+ have an Rh antigen present on the red blood cell surface.  Rh- people do not automatically have an Rh+ antibody, but they will develop if any Rh+ blood is introduced.  Rh+ blood patients will not have any antibodies.

Clinically, the Rh factor, like ABO factors, can lead to serious medical complications. The greatest problem with the Rh group is not so much incompatibilities following transfusions (though they can occur) as those between a mother and her developing fetus.  Mother-fetus incompatibility occurs when the mother is Rh- (dd) and the father is Rh+ (DD or Dd).  Maternal antibodies can cross the placenta and destroy fetal red blood cells (Hemolitic anemia, or Rh Disease).  The risk increases with each pregnancy.  Europeans are the most likely to have this problem--13% of their newborn babies are at risk.  Actually only about ½ of these babies (6% of all European births) have complications.  With preventive treatment, this number can be cut down even further.  Less than 1% of those treated have trouble.  However, Rh blood type incompatibility is still the leading cause of potentially fatal blood related problems of the newborn.  In the United States, 1 out of 1000 babies are born with this condition.

Rh Disease Good graphics


Article 4:
Genetic Engineering

Genetic engineering is the process of replacing specific genes in an organism in order to ensure that the organism expresses a desired trait. Genetic engineering is accomplished by taking specific genes from one organism and placing them into another organism.
    · Genetic engineering can only occur when scientists
      know exactly where articular genes for particular
      traits occur on specific
          > A gene map shows the relative location
            of each known gene on a chromosome.
          > Genome refers to all the genetic material
             in an organism. The Human Genome Project
             that mapped the DNA sequence of human
             genes is useful in identifying genes for
             specific traits.
    · In cloning, an identical copy of a gene or an entire
      organism is produced. This may occur naturally or
      may be engineered. Cloning brings benefits such as
      organ transplants or saving endangered species,
      but it may also result in an organism with genetic
      disorders or health problems.
    · In gene therapy, scientists insert a normal gene into
      an absent or abnormal gene. Once inserted the normal
      gene begins to produce the correct protein or enzyme,
      eliminating the cause of the disorder.  However, gene
      therapy has had limited success because the host
      often rejects the injected genetic material.

    · Stem cells are undifferentiated cells that have the
      potential to become specialized in structure or function.
      Although primarily found in embryos, they are also
      found all over the adult human body (ex: bone marrow)
      but may be harder to isolate. Therapy using stem cells
      can replace tissue that is deficient due to disease
      or damage.
    · Results of genetic engineering may include:
           >The development of plants that manufacture
             natural insecticides, are higher in protein,
             or spoil more slowly.
           >The development of animals that are bigger,
             are faster growing, or are resistant to disease.
           >The development of bacteria that produce
             hormones such as human insulin or human
             growth hormone.
           >In humans, it is theoretically possible to
             transplant copies of normal genes into the cells
             of people suffering from genetically carried 
             diseases such a Tay-Sachs disease,
             cystic fibrosis, and sickle-cell anemia.

Article 5:
Selective Breeding

Selective breeding is the method of artificially selecting and breeding only organisms with a desired trait to produce the next generation. Almost all domesticated animals and most crop plants are the result of selective breeding.

· The process works because in order for the parents to show strong expression for the trait, they must carry at least one gene for the trait.
  >Once the breeder has successfully produced offspring with the desired set of characteristics, inbreeding (crossing individuals who are closely related) continues.
  >Over several generations, the gene for the trait will become more and more prevalent in the offspring.
  >The drawback to this method is that recessive gene defects often show up more frequently after several generations of inbreeding.

· Hybridization, which is another form of selective breeding, is the choosing  and breeding organisms that show strong expression for two different traits in order to produce offspring that express both traits.  This occurs often between two different (but similar) species. 
The offspring are often hardier than either of the parents.

The NEW Genetics: Read these pages to discover how genes work, new roles/rules for RNA and DNA, life's genetic tree, the human genome, and 21st century genetics.













Can you taste PTC paper? Learn more about why humans can or cannot here.

1: T=22, NT=4
2: T=13, NT=4
4: T=  , NT=


Mendel's work:  173-178
  Genotypes/Phenotypes:  180
  Punnett Squares:  182-183
  Incomplete Dominance: 184
  Codominance:  184
  Pedigrees:  241
  Polygenic traits:  242
  Codominant/incomplete dom./X-linked traits: 244



Gregor Mendel
true breed homozygous for a trait
P Generation
parent generation
F1 Generation
offspring of P
F2 Generation
offspring of F1
influences the trait
trait can be masked
law of segregation >>>
law of independent
   assortment >>>
form of gene
genes that make up a trait
genotypic ratio
those genes' chances of occurring
how gene is expressed
phenotypic ratio
those genes' chances of occurring
Both alleles same
Both alleles different
non-sex chrom.
Cross of one trait
Cross of two traits
Punnett square
Tool to predict chances
complete dominance
One allele dominates the other, is expressed
incomplete dominance
Both alleles partially expressed; neither  dominates
Both alleles fully expressed
protein; hunts for matching antigen
protein on cell surface that elicits an immune response
Rh factor  >>>
clumping up
change in sequence of bases in DNA
    part missing
    part flipped
    part duplicated
    part switches

selective breeding
controlling the mating of organisms
mating of closest relative of organism
Crossing two different types
Formula for possible genotypes
linked genes
Always occurring together; near each other on chromosome
polygenic traits
More than one pair of alleles control phenotype



Here's a good dihybrid, X-linked trait genetics problem.  Before you look below at the answer, try to figure out the solution for yourself.  

A male that is heterozygous for type A blood and is a hemophiliac marries  a woman who's type AB and a carrier.  What are the possibilities of genotypes and phenotypes of their offspring?      

(Need a hint?.....  Remember, hemophilia is sex linked [on the X chromosome].  So, you'll need to use X and Y for part of your Punnett square, labeling the X properly.  Also, you'll need to use the alleles designated for human blood: IA, IB, i.)

answer below































Genetics Problems (w/answers) (from class)

Study Guide Key (from class)


NIGMS - National Institute of General Medical Sciences




Practice Genetics Problems

Monohybrid, Complete Dominance  (key)

M1. Create Punnett squares for the following parentage, and determine phenotypes/genotypes of offspring:
   a. Father: Heterozygous for free ear lobes (Ee)
       Mother: Homozygous for attached ear lobes (ee)

   b. Father: Homozygous for freckles (FF)
      Mother: Homozygous for no freckles (ff)


M2. Assume brown eyes (B) are dominant to blue (b).  A brown-eyed man marries a blue-eyed woman.  They have three children, two of whom are brown-eyed and one of whom is blue-eyed.  Draw the Punnett square that illustrates this family.  What is the man's genotype?  What are the genotypes of the children?


M3. In dogs, wire hair (S) is dominant to smooth (s).  In a cross of a homozygous wire-haired dog with a smooth-haired dog, what will be the phenotype of the F1 generation?


M4. In rabbits, black fur (B) dominates white fur (b).  Perform the following crosses.  Give phen/gen. for all offspring.
       a.  BB x bb             b.  Bb x Bb     c. BB x Bb


M5. Albinism is an inherited recessive condition in skin color.  The absence of the pigment melanin causes the person to be very pale with very light hair (a yellowish white) and pale eye color (cloudy blue). 
   N = dominant gene for normal skin color
   n = recessive gene for albino skin color

   a. A normal skin color man has children with a normal skin color woman.  Three children have normal skin, one is albino.  How did this happen?  Show a cross to explain this inheritance.

   b. Could any of the normal skin color children eventually pass the albino gene to their children?  Which ones?



Dihybrid   (key)

D1. In Drosophila melanogaster (fruit flies), the gene for dachs (short legs, d) is recessive to the allele for normal leg length (D).  The allele for hairy body (h) is recessive to the allele for normal body (H).  Determine the genotypes of the F1 for the following crosses:

    a. DdHh  x  DDhh                b.  DDHh  x  Ddhh                 c. DdHh  x  ddhh

    d. What proportion of the offspring from cross b would be expected to show the normal phenotype for both traits?


D2. In guinea pigs, black hair is dominant to brown hair. 
     Short hair is dominant to long hair. 
     What would be the genotypes of the following?

    a.  A fully homozygous black, long haired variety
    b.  A brown, heterozygous short haired
    c.  A brown, long haired


D3.  In peas, the allele for tall (T) plants dominate the dwarf allele (t). 
       Round peas (R) dominates wrinkled peas (r). 
       Find the phenotypic ratios and genotypic ratios of the F1 generation
       of the following crosses:

    a.  TtRR x  TtRr
    b.  Ttrr  x  ttrr
    c.  ttRr  x  Ttrr
    d.  TTrr x  ttRR



Incomplete Dominance / Codominance  (key)

IC1. Explain the difference between incomplete dominance and codominance.


IC2. In some chickens, the gene for feather color is controlled by codominance.  The allele for black is B and the allele for white is W. 
The heterozygous phenotype is known as an erminette.

    a. What is the genotype for black chickens?  

    b. What is the genotype for white chickens?
    c. What is the genotype for erminette chickens?


IC3.  If two erminette chickens were crossed,
        what is the probability that
    a. they would have a black chick?  ____ %
    b. they would have a white chick? ____%


IC4.  A black chicken is crossed with a white. 
        What's the probability they will have erminette chicks ____%


IC5.  In snapdragons, flower color is controlled by incomplete dominance
        The two alleles are red (R) and white (W). 
        The heterozygous genotype is expressed as pink.

What is the phenotype of RR?
    b. What is the phenotype of WW?     

    c. What is the phenotype of RW?


IC6.  A pink is crossed with a white. 
        What's the probability (in %) of producing a pink flowered plant?


IC7.  What cross will produce the most pink flowered plants? 
        Show the Punnett square.


IC8.  Cross someone with type AB blood with a heterozygous type A person.
        What would the phenotypes of their offspring possibly be?


IC9.  Mrs. Smith and Mrs. Jones had babies at the same maternity hospital at the same time.  Mrs. Smith took home a girl and named her Sue.  Mrs. Jones took home a boy and named him Jim.  However, Mrs. Jones was sure she had a girl and brought suit against the hospital.  Blood tests showed that Mr. Jones had blood type O, Mrs. Jones was type AB.  Both Mr. and Mrs. Smith were type B, Sue was type A, and Jim was type O.  Had a swap occurred?

Newborns at Hospital


IC10. In radishes, red and white are pure-breeding colors, while long and round are pure-breeding shapes.  The hybrids are purple and oval
The cross of a red oval with a purple oval will produce all but which phenotype?

IC 11 An incomplete dominant gene controls the color of some chickens:
          BB produces black
          BW produces a slate gray color called
blue, and
          WW produces splashed white

        A second complete dominant gene controls comp shape;
          R produces a rose comb
          r produces a single comb

        If a pure-bred black chicken with a rose comb is mated to a splashed white chicken with a single comb (P generation), what fraction of the F2 generation (from an F1 cross) will be blue with a single comb?




Sex Linked

Note: When working with sex linked (or X linked) traits, use the sex chromosome symbols X and y for the alleles in your problems.

S1. Are these statements about sex-linked traits TRUE or FALSE? 
      Prove or disprove with Punnetts and explain.

    a. A girl cannot have hemophilia unless mom does.
    b. A boy gets colorblindness from his dad.
    c. A girl cannot be colorblind unless her dad is.
    d. All sons of colorblind mothers are colorblind.
    e. Hemophiliac fathers have all hemophiliac daughters.

S2. In colorblindness, the normal male genotype is XCy, whereby the colorblind male genotype is Xcy.

    a. What is the genotype of a normal female?
    b. What is the genotype of a colorblind female?
    c. What is the genotype of a carrier?

S3. Cross a colorblind male with a carrier.  What might their children be?


S4. Can a couple who sees color normally have a colorblind son?  Daughter? 
     If these are possible, show the Punnett square.

S4. Cross a colorblind male with a perfectly normal homozygous female. 
     Can this couple produce any colorblind children?  Carriers?

S5. A hemophiliac male, whose mother and father both had normally clotting blood, marries and has 4 children with a lady who has normally clotting blood, but whose father was a hemophiliac.  Can you determine the possible genotypes and phenotypes of all the  individuals boldfaced?


Multiple Alleles

MA1. Coat color in rabbits is determined by a single gene that has at least four different alleles.  Different combinations of alleles result in four colors:  Full color (brown), Chinchilla (gray), Himalayan (black and white), and Albino (white).  Using the following information, complete the Punnett squares and answer the questions.

     C = full color, dominant to everything else
   cch = Chinchilla, dominant to ch and c
   ch  = Himalayan, dominant to c
    c  = albino, recessive to all other alleles

    a. What are the possible genotypes for an albino rabbit?
    b. What are the possible genotypes for a Himalayan rabbit? (There are two)
    c. What are the possible genotypes for a Chinchilla rabbit? (There are three)
    d. What are the possible genotypes for a full color rabbit? (There are four)

    e. C cch  x    cch cch                               Himalayan rabbit

f. C cch   x  ch ch                              Chinchilla rabbit

g. c c    x   cch     




MA2. Human hair color is controlled by one gene with four alleles
        (with some incomplete dominance):

   HBr = brown        HBd  =  blonde      hR = red    hbk = black

So, possible genotypes and phenotypes can be:

   HBdHBd  or  HBdhbk   =  blonde              HBdhR  = strawberry blonde

   HBdHBr = mousy brown                        HBrHBr  or HBrhbk = brown     

   HBrhR = auburn           hRhR or hRhbk = red             hbkhbk = black      

If someone with auburn hair has children with someone with red hair (but whose mother had black hair), what are the genotype and phenotype probabilities for their children?

Sex Linked / Dihybrid

SD1.  Find out the F1's phenotypes and genotypes.

      N - Dominant gene for normal skin color (autosomal)
      n - Recessive gene for albinism (absence of the pigment melanin)

      H - Dominant gene for normal blood clotting factors (X chrom)
      h - Recessive for hemophilia (the inability to clot)

Problem: Cross an albino male bleeder with a normal skinned carrier.

SD2. Colorblindness is a sex linked (X linked) recessive trait. 

   Males: Normal:  XCy   CB: Xcy

a. Females:  Normal: _____  CB: ______  Carrier: ______

   b. Cross a colorblind male with a female who has normal color vision (but whose father was colorblind).  Show the genotypes of all possible children.

   c. Can a normal vision male and a normal vision female produce a colorblind son?  Can they produce a colorblind daughter?

   d. Can a colorblind man and a homozygous normal color vision woman have any colorblind children?  Can they produce a carrier?

   e. Can a colorblind couple produce any normal visioned children?

Pedigree Problems

P1. Sex-Linked Pedigree pdf
P2. Pedigree Analysis in Genetics pdf
P3. Pedigree Practice Problems (with Key) pdf




Answer for problem above:


1. Step one: Determine the genotypes of the parents (diploid). 
    That is, put the word problem into symbols:

The Father: Male, heterozygous for type A blood and hemophiliac  = IAi Xhy

The Mother: Female, type AB and a carrier  = IAIB XHXh

So, your cross will be:

      IAi Xhy  x  IAIB XHXh      

 2. Step two: Determine the possible gametes that each parent could form (haploid):

        Possible sperm                Possible eggs
        IA Xh                            IA XH      
IA y                              IA Xh
i Xh                              IXH
           i y                                IB  Xh

 3. Set up and solve your Punnett square:
     What would be the resulting zygote (diploid) if THIS type sperm fertilized THIS type egg?  Put the guy's sperm possibilities across the top, and the mom's egg possibilities down the side.  Match up the letters side-by-side again.

               ♀   ♂

IA Xh IA y i Xh i y



4. Determine the genotypes and phenotypes, and their ratios.

     Note: Each square in the Punnett below exhibits a unique genotype. 
             Therefore, all are as likely to occur (1 in 16 chance). 
             The ratio would be quite long, with sixteen "1:" listed.
             GR: 1:1:1:1:1:1:1:1:1:1:1:1:1:1:1:1


     2   Type A carrier female
     2   Type A hemophiliac female
     2   Type A normal male
     2   Type A hemophiliac male
     1   Type AB carrier female
     1   Type AB hemophiliac female
     1   Type AB normal male
     1   Type AB hemophiliac male
     1   Type B carrier female
     1   Type B hemophiliac female
     1   Type B normal male
     1   Type B hemophiliac male

     PR: 2:2:2:2:1:1:1:1:1:1:1:1



Images of some proteins: 
All have a different shape. 
Don't forget: form and function go hand in hand. 
They're shaped like they are because of what they do.
You'll recognize 4hhb, 2hiu, 1igt, 1i6h, 1bkv, and others. 
(Hint, zoom your screen to 200X to read it better)


Can two medium toned people have a white or black baby?
Because three sets of alleles determine skin color
 - yes -
though the chances are 1/64...


    to top