Module 1 Practice Exam and Review Flashcards
Imagine that a human characteristic is determined by genotype only, with no environmental influence. Based on the amount of shared genetic information in MZ (monozygotic) and DZ (dizygotic) twins, would you expect concordance values to be the same or different in these two sets of twins? Give a brief explanation of your answer.
MZ twins share 100%genetic information; Dz twins share on average 50%. Therefore, if a trait is determinedby genotype only, concordance value will be different in the two tyes of twins. Values will be around 100% in MZ twins and 50% DZ twins.
You are working with a new species of beetle. You have isolated lines that breed true for either blue shells and long antenna, or green shells and short antenna. Crossing these lines yields F1 progeny with blue shells and long antenna. Crossing F1 progeny with beetles that have green shells and short antenna yield the following progeny:
blue shell, long antenna: 82 green shell, short antenna: 78 blue shell, short antenna: 37 green shell, long antenna: 43 total: 240
a. Which shell color and antenna length alleles are dominant?
b. Are the shell color locus and antenna length locus linked?
c. Check your answer to the previous question with the chi-square test.
d. If the genes are linked, calculate the recombination frequency between them.
??
Describe the centromere and kinetochore.
The centromere is the attachment point for spindle microtubules. Kinetochore is a protein complex that assembles in the centromere; later spindle microtubules attach to the kinetochore.
- Kinetochore is a protein complex. Centromere is a constricted region found on a chromosome with highly specialized, repetitive DNA sequences.
- Kinetochores assembles on the centromere.
- Centromeres are clearly visible with a light microscope as a constricted region on the condensed chromosome while kinetochrores can only be seen with the aid of an electric microscope.
- Unlike in the centromeres, three different layers can be found in the kinetochore.
- Kinetochore has corona while no such structures are found in centromeres.
- Centromeres cannot bind the microtubules. Only the kinetochores that are associated with centromeres have the ability to bind microtubules.
Your teaching assistant for class spent all night in the research lab on an experiment, and in trying to review transcription and translation keeps interchanging the words during his lecture. Which one(s) of these statements your teaching assistant has made is true?
DNA is translated into RNA by RNA ploymerase. mRNA is translated to a nucleotide sequence to make a protein. During translation, amino acids are brought to the ribosome by a tRNA molecule.
DNA is transcribed to RNA.
During translation, amino acids are brought to the ribosome by a tRNA molecule.
_______ is the change in allele frequency in a population over time.
Evolution
Which of the following statements about homologous chromosomes are true?
They are always genetically identical. They always contain the same alleles. They occur together in diploid cells. They occur together in haploid cells.
They occur together in diploid cells.
Homologous chromosomes are those that can be matched by virtue of their similar structure and function within a nucleus.
What chromosomes making up the human genome do not follow the same characteristics of homology?
sex chromosome
Chromosomes are randomly partitioned during _____ , contributing to genetic diversity.
Meiosis I anaphase
The “distance” between two linked gene pairs can be expressed as a percentage. Name the unit based on percent recombination that was created in honour of the scientist who pioneered the use of fruit flies for genetic research.
centimorgan
What inheritance is suggested by each description?
Pedigree analysis on a characteristic shows all of the following:
- males and females are affected equally.
- affected fathers may have affected daughters, but never affected sons.
- half the children of affected mothers are affected.
x-linked dominant
Crossing over (genetic recombination) occurs in…
Meiosis I prophase
A form of a gene that has a slightly different sequence than other forms of the same gene but encodes the same type of an RNA or protein, is called a(n)
allele
_____ refers to the splitting of the cytoplasm, separating one cell into two.
cytokinesis
Permanent, heritable changes in genetic information (DNA) are called
mutations
Genetically speaking, brown eyes (B-) are dominant to blue eyes (bb). However, an individual can wear colored contacts in order to change his or her eye phenotype. Suppose a man with blue eyes (bb) marries a woman who appears to have blue eyes and together they have five children. Listed below are three possible outcomes. For each of the outcomes, predict the woman’s genotype.
Three children have blue eyes and two have brown eyes
All five children have brown eyes.
All five children have blue eyes.
- The woman naturally has blue eyes (bb).
- The woman naturally has brown eyes and is heterozygous for the trait (Bb).
- The woman naturally has brown eyes and is homozygous for the trait (B
__2__ Three children have blue eyes and two have brown eyes
__3__ All five children have brown eyes.
__1__ All five children have blue eyes.
- The woman naturally has blue eyes (bb).
- The woman naturally has brown eyes and is heterozygous for the trait (Bb).
- The woman naturally has brown eyes and is homozygous for the trait (BB).
If they live long enough, the penetrance of individuals carrying the Huntington’s Disease allele will be what?
100%
If a typical somatic cell has 32 chromosomes, how many chromosomes are expected in each gamete of that organism?
16
Which term refers to mating between closely related people?
consanguinity
In eukaryotes, chromosomes do not contain:
proteases
During the cell cycle, chromosomal replication occurs in
Interphase
In order to be functional, a chromosome requires all of the following except:
centromeres
origins of replication
nucleomeres
telomeres
nucleomeres
In the following tetrahybrid cross AaBbCcDd x AaBbCcDd what proportion of the F2 offspring would be expected to be genotypically AaBbCcDd ?
81/256
4/256
8/256
1/16
1/16
Ability to roll the tongue is caused by a dominant allele. A woman is a “roller,” but one of her parents is not.
The woman is expecting a child with a man who is a “nonroller.” What is the probability that their child will be a “roller”?
Ref 6-2
1/2
Homologous chromosomes move toward opposite poles of the dividing cell during
meiosis I