Genetics Study Guide

Topics are listed below. Students are responsible for creating a study guide here.

  • All living things contain DNA.
  • DNA is the " language of life" because it is the gentic material that codes for all orgainisms.
  • Guess what? The code only contains FOUR LETTERS: A,G,T,C.
DNA is found in repeating units called nucleotides,phosphate sugar, base. " Backbone of DNA".

The four letters for DNA.
  1. Thymine-
  2. Adenine
  3. Cytosine-
  4. Guanine-
  • Thymine and Adenine bond.
  • Cytosine and Guanine bond.
    • DNA is double-stranded.

Gene: Region on a chromosome that codes for a specific polypeptide ( protien).
When the gene's specific DNA code is read (expressed) by the cell, a polypeptide is created.
Question: How is the gene read?
  • The section of DNA get copied on to a strand of RNA ( transcription)
  • Then the DNA is read at a ribosome ( translation)

Chromosome: As a Cell prepares to divide the DNA becomes condensed into compact structures called: Chromosomes. ( Chromo: colored) ( some: bodies)
Offspring get DNA from parents inheriting Chromosomes.
  • In humans, each body cell has 46 chromsomes in two sets ( 23 pairs)
  • One set of chromosomes come from the mother and one set comes from the father.
XX- female
XY- Male
  • For males anything sex-linked goes in the X not Y. Example: XcY

mRNA: The guide for protein synthesis and the type of RNA that carries DNA from the nucleus to the ribosome sites of protein compounds in the cell, hence the name mRNA (Messenger RNA).
Transcription: messenger RNA is made by copying the DNA
Translation: messenger RNA is read by the ribosomes who then create proteins
Codon: when genetic information is encoded as a sequence of 3 bases in a row;make amino acids
Amino acid: The building block of protein; critical to life
Egg: The mother puts 23 chromosomes in her egg.
Sperm: The father puts 23 chromosomes in his sperm. When it enters the egg, it joins to make the 46 chromosomes in each cell.
Zygote-the cell formed by the union of two gametypes
Genotype-the genetic MAof an organism
Phenotype: physical appearances
Homozygous:Having identical alleles for a single trait.
Heterozygous:Having two different alleles for a single trait.
Dominant - 1 allele overpowers its normal counterpart
Recessive - heterozygous, but faulty allele does not affect the person
Codominance: occurs when both alleles are neither dominant or recessive
Sex-linked disorders: characteristics that are found on the sex chromsomes
Heterozygote advantage: When the heterozygote genotype has a higher relative ability to produce than the homozygote dominant or homozygote recessive genotype
Polygenic: Refers to physical characteristics
Mendel- Gregor Mendel is known as the "Father of Genetics" and is most popular for his study of pea plant traits.
Vitamin D: The key in healthy bones and teeth. It can be obtained in sunlight exposure. Lack of Vitamin D can lead to liver or kidney disorders or cause diseases, such as rickets.
Folic Acid:Folic acid is a B vitamin. It helps the body make healthy new cells. Folic acid is also destroyed by too much sun.
Mutation -any event that changes genetic structure; any alteration in the inherited nucleic acid sequence of the genotype of an organism

1. Why do different skin colors exist in humans? How did they evolve?
When DNA is transcribed or copied into mRNA (messenger RNA) there is a possiblity for mutation or a fault in the coding process because of this, the protein that codes or melain maybe higher or lower then the original strand of DNA coded for, therefore having a different skin color. Because sun helps the body get vitamin D and also destroys folic acid, there was a problem for people who spent too much time in the sun and people who spend not enough time in the sun. In places like Africa, where there is no shade, people are outside a lot and their skin is darker so they can get enough vitamin D without losing too much folic acid. In places like Alaska, where it’s very overcast and people are not outside a lot, their skin is lighter to let in a lot of vitamin D and they won’t loose as much folic acid anyways.
2. With regards to blood type, who is considered the "universal donor"? The "universal receiver"? Why?
The universal donor is type O, because Type O has no molecules so it is able to merge with any molecule. The universal reciever is type AB because it has both Type A molecules and Type B molecules so it can recieve blood from all Types. The molecules have to recognize similiar molecules in order to fuse together.
3. What does DNA code for? How does it do this? What are the steps? Be able to complete the steps using the DNA Decoding Circle given to you when we played Codon Bingo.
-DNA codes for proteins.
-It transcribes it into mRNA.-mRNA codes for the various amino acids.
When mRNA is coded it changes Thymine to Uracil which is a nitrogen base.
4. What is heterozygote advantage? How does that relate to sickle cell anemia and malaria?
Heterozygote advantage is when a heterozygote is healthier than a homozygote due to their surroundings. For example, someone in Africa can be a carrier of sickle cell and not be affected by sickle cell disease at all and malaria does not affect them either. Therefore, it is better to be a carrier in Africa than a homozygote because they can get malaria.

5. What determines an organism's phenotype?
An organism's Genotype determines it's phenotype.
6. Why are males more likely to have a sex-linked disorder?
The males are most likely to get a sexed-linked disorder because they only get one X chromosone and females get two. Females have a back up X chromosone, while men only have one X chromosone so if they get a disorder in the chromosone, they automatically get that disease.

7. How is DNA packaged? What does it look like? How does DNA explain the Unity and Diversity of all living things?
DNA is packaged in chromosomes. They are linear. DNA is the same in all living things however we are all diverse. We are 99.9% alike however one difference, such as an A in place of a C would change us completely.
8. What is a punnett square? Why is it set up the way that it is? Make sure you can not only make punnett squares, but also analyze them.
It's a grid used to show all the outcomes of all possible traits in a zygote. it is set up to show what both parents contribute. It also shows whether the zygote will be heterozygous or homozygous.

9. What are pedigrees used for? Make sure you can draw a pedigree and use it to solve inheritance problems.
A pedigree is used for tracking the genotype of a family. It can be used to track sex linked disorders.