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BIO.B.1.2 Explain how genetic information is inherited.
BIO.B.1.2.1 Describe how the process of DNA replication results in the transmission and/or conservation of genetic information.
BIO.B.1.2.2 Explain the functional relationships between DNA, genes, alleles, and chromosomes and their roles in inheritance.

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BIO.B.2.1 Compare Mendelian and non‐Mendelian patterns of inheritance.
BIO.B.2.1.1 Describe and/or predict observed patterns of inheritance (i.e., dominant, recessive, co‐dominance, incomplete dominance, sex‐linked, polygenic, and multiple alleles).
BIO.B.2.1.2 Describe processes that can alter composition or number of chromosomes (i.e., crossing‐over, nondisjunction, duplication, translocation, deletion, insertion, and inversion).

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BIO.B.2.2 Explain the process of protein synthesis (i.e., transcription, translation, and protein modification).
BIO.B.2.2.1 Describe how the processes of transcription and translation are similar in all organisms
BIO.B.2.2.2 Describe the role of ribosomes, endoplasmic reticulum, Golgi apparatus, and the nucleus in the production of specific types of proteins.

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BIO.B.2.3 Explain how genetic information is expressed.
BIO.B.2.3.1 Describe how genetic mutations alter the DNA sequence and may or may not affect phenotype (e.g., silent, nonsense, frame‐shift).

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BIO.B.2.4 Apply scientific thinking, processes, tools, and technologies in the study of genetics.
BIO.B.2.4.1 Explain how genetic engineering has impacted the fields of medicine, forensics, and agriculture (e.g., selective breeding, gene splicing, cloning, genetically modified organisms, gene therapy).



REPLICATION Check yourself
1) What 4 base pairs make up the nitrogen bases (rungs) of the DNA double helix?
2) a)Which are purines and which are pyrimidines; b) what distinguishes the the way A bonds to T vs. C bonds to G (hint: H-bond numbers)?
3) Which pair with which when making DNA?
4)What enzyme unzips the original DNA from the parent cell in order to begin the process of copying it?
5)Which sets of nitrogen pairs are easier to separate for the helicase and why?
6)The backbone of DNA is made alternating molecules of what in BETWEEN the rungs and what attached to the rungs?
7)On which side of the screen (left strand or right strand) does the DNA run 5' to 3" top to bottom and on which side does it run 3" to 5" top to bottom?
8)On which side of the screen will be the leading strand and which the lagging strand during replication?
9)What purpose does starter RNA Primase serve?
10)What are Okazaki fragments?
11)What purpose does exonuclease serve?
12)What purpose does ligase serve?



For an online lesson in Mendel's Pea genetics, click here:

Gregor Mendel
F1 Offspring
F2 Offspring
incomplete dominance
Punnett Square

1. A characteristic that can be inherited is a ___ (trait, nucleotide).
2. Pieces of DNA that are alternate versions of one trait (for instance peas can be green or yellow)are called _.
3. A specific section of DNA that codes for a characteristic in an organism is a _.
4. The stdy of inheritance and the way DNA is passed down to offspring is called _.
5. Father of modern genetics and inheritance was a monk named_
6. A synonym for homozygous, this term was used by Mendel to designate peas that for generations after generations never produced offspring with a different trait than themselves for a certain gene.
7. A synonym for heterozygous, this term was used by Mendel to designate peas that were in the F1 gereation and when cross-bred, they showed offpring with a 3 to 1 ratio.
8. A coiled section of DNA with specific sections of genes on its telomeres.
9. A specific site on a chromosome or its homologue where the alleles for any specific gene are located.
10. First generation hybrid offspring of 2 purebred parents with the varying alleles for a trait.
11. Having 2 of the exact same alleles for a specific trait (PP or pp).
12. Having one of each variation of the different alleles for a specific trait (Pp).
13. The offspring of 2 hybrid parents.
14. A chart reated to predict the way homologous chromosomes can move into gametes to donate different alleles to their offspring.
15. When both alleles express themselves equally in offspring (ex. black and white spots).
16. When neither allele expresses itself entirely in offspring so a blend is observed (ex. red allele + white allele = pink offspring).
17. The outward appearance that a set of alleles shows in an organism (ex. purple)
18. The actual alleles that an organism has for a trait (ex. Pp).

Gregor Mendel, was a monk in Austria in the mid-1800s who raised peas in the monastery gardens. While breeding his peas, he made some big discoveries. They were discoveries about genetics.
The peas had several traits he could see. Some plants were tall and some were short. Some had wrinkled pods and some had smooth pods. Some pods were green and some where yellow. The flowers were white or purple. Mendel looked at each trait and learned how they were passed down to the offspring plants. Since plants breed using
pollen, Mendel controlled which plants pollinated other plants. This was how he discovered many important genetic rules.

How an individual looks and what their genetic code is sometimes do not match up. This is the difference between genotype and phenotype. The genotype is the actual genetic make up of an individual. The phenotype is what that individual looks like.

Traits that show up more often are called dominant traits. Traits that show up less often are called recessive traits. If an individual with dominant traits breeds with an individual with recessive traits, this can result in a hybrid offspring. Hybrid individuals can look like they have dominant traits (phenotype), but actually be hybrid (genotype).
Hybrid plants are different from dominant plants even if they looked the same. Each gene has two chances at a trait – two copies — two alleles. So a hybrid plant could be carrying the allele for a recessive trait even if you can’t see it. So, for example, a hybrid plant might be tall like its dominant parent, but it still could have an allele for shortness that you don’t see. This is the difference between genotype and phenotype. The genotype is the actual genetic make up of an individual. The phenotype is what that individual looks like.

This can be illustrated with a simple chart. It’s called a Punnett’s Square.


Let's look at a MONOHYBRID CROSS of two heterozygous parent plants for the trait of flower color (purple & white). Observe the Punnett square, Answer the questions below using the Punnett.

1) What type of dominance is exhibited by pea flower color genes?
2) Which color is the dominant allele?
3) What letter represents the dominant allele?
4) Which color is the recessive allele?
5) What letter represents the recessive allele?
6) What would a heterozygous pea flower look like if this trait was governed by the rule of CODOMINANCE?
7) What is the expected PHENOTYPIC frequency of flowers the offspring? (%white & %purple)
8)What is the expected GENOTYPIC frequency of the offspring? (%homozygous dominant,%homozygous recessive, %heterozygous)
9)What would be the expected PHENOTYPIC outcome if one of the parent plants was homozygous dominant and the other heterozygous? Draw a punnett square to support your claim.
10) What would be the genotypic and phenotypic outcome if you had a monohybrid cross of two homozygous recessive pea plants? Draw a punnett square to support your claim.

Patterns of Inheritance

Mendelian Complete Dominance
Incomplete Dominance
Multiple Alleles

Look at the example of the monohybrid cross of the red & white flowers below and answer the following questions.
external image incomplete%20dominance.jpg
external image incomplete%20dominance.jpg

11) What is the phenotype of the rr flower?
12) What is the gentoype of the red flower?
13) Look at the F1 (1st Filial) offspring of the P(parents) plants and decide: what type of dominance governs flower color alleles for this flower species? Explain how you know this.
14) Why would crossing a pink flower with a white flower NEVER produce a red offspring?


Use this tutorial to learn dibybrid crossing in mendelian genetics:

16) Pea color and flower color are both governed by complete dominance in pea plants with Yellow dominant over green peas and Purple dominant over white flowers. Using Yy and Pp, cross a female pea plant heterozygous for both traits with a male plant homozygous recessive for both traits. Show the dihybrid cross Punnet AND list the expected genotypic and phenotypic frequencies of both traits in the offspring.

FEMALE: heterozygous for both means YyPp
MALE: homozygous-recessive for both means yypp

Make the ova: yp,yp,yp,yp
Make the sperm: YP, Yp, yP, yp

Make your Table and plug in your allele combos:




Expected Phenotypic Frequencies/Ratios of Offspring
% green peas & white flowers
% green peas & purple flowers
% yellow peas & white flowers
% yellow peas & purple flowers


Blood Type Genetics in Humans
Earlier in the semester, we learned that the cell membrane has integral and peripheral proteins embedded within that serve as identification markers to the immune system. Human red blood cells (one of the few cells in the human body without a nucleus) can have two different types of protein markers (antigens) sticking off of there membranes. A antigens and B antigens. The gene for the presence of antigens and what types on the membrane has three possible alleles (variations). IA codes for A antigens. IB codes for B antigens. IO codes for the presence of NO antigens on the membrane. But wait!!! It gets tricky. Observe these rules for the expression of blood type antigens on red cells:

1) IO is recessive to both IA and IB
2) IA and IB are governed by complete dominance over IO but by codominance when in each other's presence
3) People with A blood have antibodies against B antigens in their plasma because B is a foreign protein; people with B blood have antibodies against A blood; people with AB blood have NO antibodies agaisnt either or they would attack their own cells; people with O blood have both anti-A and anti-B antibodies!!

see the chart below
1) name all of the possible allelic combinations (genotypes) for Type A blood phenotype
2) name all of the possible allelic combinations (genotypes) for Type B blood phenotype
3) name all possible allelic combinations (genotypes) for Type AB blood
4) name all possible allelic combinations (genotypes) for Type O blood
5) How many alleles are there in the human population for blood type with regards to the red cell antigens?
6) How many alleles does any one person have in their DNA for this trait?
7) There is question that perhaps two babies with tag switched in the maternity ward of the hospital. This information is known about the parents.
*Saheed has type O blood and his wife Layla has type A blood.
a) do a punnett square showing expected offspring frequencies (both geno and phenotypic) if Layla is heterozygous in genotype, then do one if she is homozygous.
*Antwan has type B blood and his wife Angelina has type AB blood.
b) do a punnett square showing expected offspring frequencies (both geno and phenotypic) if Antwan is heterozygous in genotype, then do one if he is homozygous.
c) if Baby 1 is a type O and baby 2 is a type A...Which baby belongs to which couple?
8) Google Rh factor and explain how this genetic trait is governed and inherited.


"when genes are housed on the X or Y chromosomes"
Suppose fruit fly eye color is sex-linked , specifically
x-linked. Suppose that the R allele codes for red eyes and the r (or w here) codes for white eyes. A female can have red eyes if she is homozygous RR or heterozygous Rw. The only way she has white eyes is if she is ww. A male only has one X chromosome and the eye color is found on the X males only have ONE allele for eye color wityh no chance to be heterozygous.

Thus, males have a higher chance of having white eyes.

There are 3 types of chromosomes in the human genome depending upon how they wind up during Prophase:
  • Metacentric – centromere in the middle of the chromosome
  • Submetacentric – centromere divides the chromosome into 1/3 and 2/3
  • Acrocentric – centromere near the end of the chromosome

This is a karyotype (look at all 46 chromosomes/23 pairs of chromosomes in the human genome) from a normal human.

Check yourself:
1) How many pairs of chromosomes does your full DNA strand in each cell house?
2) Which chromosome number seems to be the longest single chromosome in human karyotype?
3) Are all of the human chromosomes shaped the same? Formulate a sentence that describes the comparative look at all 23 chromosome numbers in the human genome.
4) Can you tell just by looking at the pairs which chromosome came from this individual's Mom (her egg) and which from their Dad (his sperm)?
5) What name do we give these pairs of chromosomes that code for the same genes but one came from Mom and one from Dad?
6) Describe how one could look at the chromosomes in an individual's karyotype and decide whether it is a male or a female.
7) Name the metacentric chromosome number.
8) Name the submetacentric chromosomes in the human genoime.
9) Name the acrocentric chromosomes.
10) What pair number determines the sex of a human?


There are an estimated 20,000 to 25,000 total genes in the human genome. these are carried on the 23 pairs of chromosomes in your DNA.

Using the internet, look up the human chromosome number that matches your seat number in class. Create poster that shows that
chromosome include the following:
a) Place a very visible title at the top, bottom or side of the poster: ex. HUMAN CHROMOSOME #5 ...and your name, date & period
b) Sketch your chromosome. Be mindful of the placement of the centromere as not all are the same.
Do your best to show the stain banding that occurs UNIQUELY ON THIS CHROMOSOME when stained for viewing under a light microscope.
c) identify the chromosome's shape class
· Metacentric – centromere in the middle of the chromosome
· Submetacentric – centromere divides the chromosome into 1/3 and 2/3
· Acrocentric – centromere near the end of the chromosome
d) list the approximate number of genes coded for by that chromosome
e) label the locus for at least 5 potential diseases or disorders that can occur as a result of genes on this chromosome
f) label at least 10 more loci other than the diseases and the specific protein or trait coded for at this locus
g) list the approximate number of bair pairs (rungs) on this chromosome


1) Know all of the vocabulary from the unit and understand them in context as they relate to genetics.
2) Be able to do Punnet Square expected offspring frequency predictability problems for monohybrid and dihybrid crosses.
3) Understand the 6 patterns of inheritance (complete dominance, incomplete dominance, codominance, multiple allele system, plieotropy, polygenic inheritance) and how epistasis can affect traits.
4) Be able to predict Blood Typing Genetics outcomes and explain how and why there is a universal donor(O) and universal acceptor(AB).
5) Understand karyotyping and be able to tell the sex of an individual from their karyotype. Know the types of chromosomes and how to tell them apart according to shape.
6) Be able to determine how sex-linked disorders/traits have a unique expected frequency outcome depending upon the sex of the individual and the chromosome the trait is linked to.
7) Understand the role that crossing over and independent assortment in Meiosis play in inheritance.

Genetics Games