HEREDITYFinal Exam Study Guide

Name:_______________________________________________________ period:_____

1. What is DNA replication? A new strand of DNA is made using an existing piece of DNA as a template.

a. Where does it occur? In the nucleusb. Why is it called “semiconservative”?Each new piece of DNA contains one strand from the original DNA and one “new” strand (generated from adding nucleotides complementary to the original strand.)

2. What is transcription? A piece of mRNA is made using a DNA template.

a. Where does it occur? In the nucleus

3. What is translation? A protein is made using an RNA template. mRNA carries the message in CODONS. tRNA transfers amino acids to the strand in the

correct order using ANTICODON to codon matching.

a. Where does it occur? cytoplasm

b. What organelle is involved? Ribosome (made of rRNA)

4. Why do replication and transcription ALWAYS have to occur in the nucleus of a eukaryotic cell? DNA cannot leave the nucleus. (And both require a DNA template)

a. Would this be true in a prokaryote? NO- they do not have a nucleus, just a nucleoid region

Use the codon chart to answer the questions that follow. (Choose A, B, C or D)

Match the following consequences to the mutation that would cause them.

A. the amino acid sequence would be shorter than expected

B. the identity of one amino acid would changeC. the identity of more than one amino acid

would changeD. the amino acid sequence would remain

unchanged

5. _B___ If the original strand of AUG CCA UUG CAU was changed to AUG CAA UUG CAU

6. _A___ If the original strand of AUG CCA UUG CAU was changed to AUG CCA UAG CAU

7. __D__ If the original strand of AUG CCA UUG CAU was changed to AUG CCA UUA CAU

8. _C___ If the second C in CCA was deleted from the original strand of AUG CCC AUU GCA U

9. What is a germ cell? How does it differ from a somatic cell?Somatic cells refer to those cells that make up the body (aka body cells). These cells contain the diploid number of chromosomes. In humans this number is 46. Germs cells are those cells associated with the gametes of an organism. These cells have half the number of chromosomes and are haploid. In humans, this number is 23.

10. How would getting a mutation in a germ cell affect organisms differently than a mutation in a somatic cell?

Germ cell mutations can be passed from parent to offspring. Somatic cell mutations are not

11. Compare and contrast a point vs frameshift mutation. Which usually causes more damage to the protein?

Both mutations will alter the sequence of nitrogen bases in the DNA. A point mutation changes/replaces one nitrogen base with another in the sequence of DNA. This may or may not alter the amino acid that will be coded for. A frameshift mutation will add or delete nitrogen bases changing how the codons will be read at the ribosome. A frameshift mutation will change all of the amino acids after the point of insertion or deletion.

Use this diagram to answer the next few questions.

12. What macromolecule is being made through the process pictured above? ____Protein___________.

13. Which organelle is closely associated with the process represented in the diagram?_Ribosome____

14. Which amino acid would be added to the chain at the position of codon CUU?__Leucine_________.

15. When writing the offspring ratios for dihybrid crosses, what order will you always report in?

Dominant, Dominant: Dominant, recessive: recessive, Dominant: recessive, recessive

16. What parent combinations will give you the following ratios:

a. 3:1 __Aa x Aa__________________

b. 2:2 __Aa x aa__________________

c. 9:3:3:1 __AaBb x AaBb_____________

d. 1:1:1:1 __AaBb x aabb______________

17. We studied many different patterns of inheritance. Briefly describe each type below. Be able to read a pedigree for each type

a. Simple Mendelian traits (T= tall, t= short) Involves the inheritance of one trait. For example tall plants are crossed with short plants. If tall is dominant, predict the genotypic ratios of the F1

b. Dihybrid Crosses Involves the inheritance of two traits. For example tall plants with yellow seeds are crossed with short plants with green seeds.

c. Sex-linked traits (on the X chromosome) This involves the inheritance of traits located on the X chromosome. These traits include color blindness and muscular dystrophy. Males are more likely to express these recessive conditions because males only need one of the recessive alleles whereas females need two.

d. Incomplete Dominance: When two organisms are crossed for a particular characteristic, an intermediate phenotype may result. For example, when a red flower is crossed with a white flower, pink flowers are produced.

e. Codominance When two organisms are crossed for a particular characteristic, both characteristics appear in the phenotype. For example, when a red flower is crossed with a white flower, red and white flowers are produced.

f. Multiple Alleles: More than two alleles exist for a particular trait. For example, in human blood types individuals can be blood type A, B, O, or AB

18. Your liver cells perform a very different function from you nerve cells. They have very different shapes, make different proteins and even have a different life span. If every cell in your body has the same DNA, how do you think these differences could occur?Different genes are turned on or off in these different cells causing them to perform different functions.

19. Watson and Crick expanded on research performed by Rosalind Franklin to discover the structure of DNA. Explain the following terms they used to describe its structure.

a. Complementary base pairs A always pairs with T and G pairs with C

b. Double Helix The structure of DNA is composed of two strands that twist resembling a twisted ladder. This unique shape is known as the double helix.

c. Genetic Code for making proteins Genes are segments of DNA. These segments of DNA contain the information needed to make proteins.

20. In corn, purple kernels (D) are dominant over yellow (d), & smooth kernels (G) are dominant over shrunken (g). How many phenotypes are there?(n=__4_) Degrees of Freedom: ((n-1)= __3__)

An ear of corn is found to have 381 kernels. 216 are purple, smooth 79 are purple, shrunken 65 are yellow, smooth21 are yellow, shrunken

Based on these results, it was suspected that both parents were heterozygous for each trait. A Chi Square analysis was performed on the data. The null hypothesis and results are show below.

Null Hypothesis: There is no significant difference between the expected 9:3:3:1 and observed ratio. Any difference is due to chance.

purple, smooth purple, shrunken yellow, smooth yellow, shrunken

Observed 216 79 65 21Expected 214 71.5 71.5 24

Calculated Chi Square value x2= 1.771

21. Should you accept or reject the null hypothesis? Explain why? With three degrees of freedom and a x2 value of 1.771 we need to accept the null hypothesis due to the fact it is below the critical value at .05. The observed data “fits” the predicted ratio.

22. Which man is the biological father of this baby? Male 1 Use the following gel electrophoresis.

23. The gel electrophoresis below shows the DNA banding patterns for a blood stain found at a crime scene and 4 suspects. Which of them is probably the culprit? John

24. How were these bands created? (What are they actually made of? What is the name of the enzyme used to cut it?) The bands are segments of DNA. In order to produce these bands a long strand of DNA was cut using restriction enzymes. The resulting fragments were then pulled through a gel like substance that separated the different fragments based on their length. The smallest fragments are at the bottom of the gel and the longest fragments remain close to the top.

25. Below is another gel. How is the gel pattern created? (Why do some pieces move farther than others? Why are some bands thicker than others?) The thicker bands in the gel represent many fragments of DNA that are the same size accumulating in the same location in the gel.

26. In Meiosis we studied a concept called independent assortment. The picture below illustrates this using eye color and hair color. Explain how this creates diversity among organisms and determine what combinations of gametes can be formed in this example

brown hair blonde hairblue eyes brown eyes

When the homologous chromosomes pair up during meiosis I they can alter their arrangement resulting in different gametes. For example, the chromosome containing the blonde hair gene doesn’t always need to line up on the right side of the cell above the chromosome containing the brown eye gene. It could have just as easily positioned itself on the left side of the cell along with the blue eye gene.

27. Some traits are called “linked” because they occur on the same chromosome and therefore are often inherited together. One such linkage is red hair and light complexion. How would this change the possible combinations in the gametes? Draw a picture to help illustrate the difference.

If genes are linked and located on the same chromosome, they do not segregate and separate independently of eachother.