Final Exam Flashcards
Synonymous
Mutation that does not change the amino acid
Transition
Substitutions of a purine for a purine base
Meiosis
Creation of four daughter cells from a single parent cell
Transversion
Substitutions of a purine base for a pyrimidine base
Chromatin
DNA with a protein scaffold
Quanternary
A higher order of structure involving more than one protein
Peptide
Chemical bonds connecting amino acids
Mitosis
Formation of two cells from one cell
Tertiary
Describes the three dimensional structure of a protein
Phosphodiester
Bonds formed along the pentose sugar backbone of a polynucleotide
Nucleosome
the fundamental repeating unit of chromosome
Heterochromatin
Stains more darkly and has inactive genes
Neutral
missense mutation that changes one AA for another chemically similar AA
Euchromatin
Stains lightly and has active genes
Nucleotides (A,C,G,T,U) are classified into two categories based on their ring structure. _______ have a single ring and are “CUT” from _______ which have a double ring structure
Pyrimidine
Purine
Characteristics of a model organism
inexpensive to raise and keep
ability to adapt to a lab environment
short generation interval
lots of offspring
Eukaryotic cells have the majority of their DNA present in the nucleus but they also have organelles in the cytoplasm that contains their own DNA. We listed two fundamental differences between the DNA contained in the nucleus and the DNA contained in the mitochondria/chloroplast. What are those two characteristics of mtDNA and cpDNA
Circular
Uniparental inheritence
T/F
The nitrogenous base in nucleic acids is attached to the 1’ carbon of the pentose sugar
True
T/F
The regulatory promotor of a gene is located immediately upstream of the transcription start site which is immediately upstream of the core promotor
F
Core promotor site is immediately upstream of the TSS
T/F
Exons must be spliced out of the pre-mRNA molecule so that only the introns are left in the mature mRNA
F
Introns must be spliced out of the pre-mRNA molecule so that only the exons are left in the mature mRNA
T/F
Enhancers function to control gene expression and are typically upstream of a gene but can also be downstream from the coding region
True
T/F
Okazaki fragments are fragments of DNA that occur on the leading strand during DNA replication
False
Occur on lagging strands
T/F
Replication of DNA is initiated by RNA primers that are later removed
True
When Meselson and Stahl designed their experiments to determine how DNA replicates, they could have chosen to radiolabel any number of different elements. Why did they choose to label nitrogen?
It is an essential component of DNA
During nucleic acid polymerization, two phosphate groups are cleaved from the incoming dNTP providing the energy needed to form a bond between the previously incorporated nucleotide and the incoming nucleotide. Why is it important that this energy comes from the incoming nucleotide versus from the existing nucleotide of the growing chain?
What is the name of the modification that is added to eukaryotic pre-mRNA very shortly after transcription begins and it functions to stabilize the pre-mRNA and is necessary for initiation of translation
5’ cap
Poly A Tail
Polynucleotides (DNA/RNA) are polymers of nucleotide subunits. Similarly, all proteins are polymers composed of what subunit?
Amino acids
Crossing over (recombination) is an important source of genetic variation. which of the following is true of recombination?
A. it allows for multiple protein isoforms to e translated from one template
B. It occurs during prophase
C. it occurs during both mitosis and meiosis
D. both (a) and (b) are true
E. None of the above are true
B. it occurs during prophase
A cell in G1 stage of development contains 2 total chromosomes. How many chromosomes would be present in a cell from the same organism if it were in:
a) anaphase I of meiosis
B) Prophase of mitosis
A) 4
B) 2
There were three early theories as to the model of DNA replication. Which model ended up being proven correct
semiconservative
What are the three basic building blocks of a nucleic acid?
Pentose sugar
phosphate linker
nitrogenous base
Even before nucleic acids were identified as the genetic material, biologist recognized that, whatever the nature of the genetic material, it must possess four important characteristics, what are they?
Ability to store info
Ability to copy info
Ability to retrieve info
Ability to vary
If a double stranded DNA molecule is 15% cytosine, what are the percentages of all the other bases in the molecule
15% cytosine
15%G
35% A
35% T
When DNA replicates (is copied), at each replication fork, synthesis of the leading strand proceeds continuously and that of the lagging strand proceeds discontinuously. Discontinuous replication on the lagging stand is a result of which property of DNA?
antiparallel nucleotide strands
Which of the following phrases does not describe a function of a promotor
a) serves as a sequence to which transcription machinery binds
b) signals where transcription ends
c) determines which DNA strand is the template
d) all the above are functions of the promotor
b) signals where transcription ends
DNA and RNA have directionality (polarity) based on the 5’ and 3’ ends of which building block of the nucleic acid molecule,
pentose sugar
Proteins also have directionality based on the individual building blocks of the molecule. We describe the directionality of a protein based on the ______ and ______ ends of the molecule
amino
carboxy
The genetic code is said to be ______, i.e. more than one triplet of nucleotides can code for a single amino acid
degenerate
The process of translation to synthesize a protein stops when the ribosome encounters a stop codon. How or why do the stop codons stop translation?
There are no tRNAs for stop codons
In eukaryotic organisms, why does DNA replication start at many locations along the DNA molecules?
To speed up the process since there is alot of DNA to replicate
There were two very important processes that occur in meiosis that contribute to the creation of genetic variation. What are those two processes called
crossing over
independent assortment
The primary sequences of both DNA and RNA are capable of forming higher level secondary structures. What is the common secondary structure of DNA
Double helix
What is the one main reason we discussed that allows RNA to form more types of secondary structures than DNA
It is double stranded
Common four step pathway that the cell uses to repair DNA. What are these four steps and give a brief description of each step
Detection-finding the error
Excision-Removing the mistake/cutting it out
Polyadentalation-adding in the new info
ligation-ligase seals it up
Penetrance
percentage of individuals with a particular genotype that express the phonotype expected of that genotype
a posteriori
translated as ‘from the later’
Epistatic gene
gene that masks or suppresses the effect of a gene at a different locus
Turner syndrome
human condition in which cells contain a single X chromosome and no Y chromosome
Kleinfelter Syndrome
Human condition in which cells contain one or more Y chromosomes along with multiple X chromosomes
a priori
translates to ‘from the earlier’
hypostatic gene
gene that is masked or suppressed by the action of a gene at a different locus
expressivity
degree to which a trait is expressed
Sex-limited
characteristic encoded by autosomal genes and expressed in only one sex
Sex-influenced
characteristic encoded by autosomal genes that are more readily expressed in one sex
When Mendel began his experiments with pea plants he began by creating true breeding lines for a single trait. Explain why this was an important first step in his experiment
The true breeding lines acted as his control groups. If he knew what they produced every time he could then cross them with something else and know what the true breeding ones contributed vs. what the unknown contributed
If the probability of being blood type A is 1/4 and the probability of being blood-type O is 1/4 what is the probability of being either blood type A or blood type B
1/4+1/4
1/2
A condition in which one allele masks the expression of another allele at a single locus is called
dominance
Based on Mendel’s work, he drew some conclusions that are now known as Mendel’s Laws. What are the names given to these two laws and provide a description of the observations for each of these laws
Segregation
-each trait has two alleles
-alleles are segregated when the gamete forms
-alleles segregate evenly
Independent assortment
-traits/genes at different loci are sorted independently of each other
Assuming births are equally likely to be male or a female, if a mating produced 3 males, what is the probability that the next child will also be male
1/2
What is the difference between a locus and an allele
locus is the location of a gene
allele is a variation of the gene
What is the difference between a genotype and a phenotype
genotype-what is available to be expressed, what type of genes they have
phenotype- what is expressed, physical traits
For a locus with 4 multiple co-dominant alleles, how many genotypes are possible
10
Sickle cell anemia is an autosomal recessive trait in humans. in across between two parents, both of whom are carriers of the sickle-cell allele, what is the probability that their first two children will carry the deleterious allele
1/4
In sheep, lustrous fleece results from an allele (L) that is dominant over an allele (l) for normal fleece. A ewe with lustrous fleece is mated with a ram with normal fleece. The ewe then gives birth to a single lamb. What would the phenotype of that single lamb have to be in order to definitively determine the genotype of the mother.
normal fleece
indicated mom is Ll
Hemophilia is an X-linked recessive disease in humans. A woman with hemophilia mates with a man who exhibits normal blood clotting. What is the probability that their child will have hemophilia
1/2
Homozygosity of an allele at one locus that masks the phenotype of a second locus is described as
Epistasis
Alkaptonuria is a metabolic disorder in which affected people produce black urine. Alkaptonuria results from an allele (h) that is recessive to the allele for normal metabolism (H). Sally has normal metabolism, but her brother has alkaptonuria. Sally’s father has alkaptonuria, and her mother has normal metabolism.
Give the genotypes of : Sally, her mother, her father, and her brother.
If Sally’s parents had 4 more children, what is the probability that all 4 children will have alkaptonuria
If sally marries a man homozygous for the normal allele at the alkaptonuria locus, what is the probability that their first child will not have alkaptonuria?
Sally’s Mother-Hh
Sally’s Father-hh
Sally-Hh
Sally’s brother-hh
1/2 x 1/2 x 1/2 x 1/2=1/16
4/4=1
In mice, an allele for apricot eyes (a), is recessive to and allele for brown eyes (a+). At an independently assorting locus, an allele for tan coat color (t) is recessive to an allele for black coat color (t+). A mouse that is homozygous for brown eyes and tan coat color is crossed with a mouse homozygous for having apricot eyes and a black coat. The resulting F1 are intercrossed to produce the F2. In a litter of 8 mice, what is the probability that four will have apricot eyes and tan coats.
Parental genotypes- a+a+ x aat+t+
F1 gentotypes- a+att+ x a+att+
Probability of obtaining four F2 with apricot eyes and tan coats-
Plumage patterns in mallard duck is determined by multiple alleles. One allele M produces the wild-type mallard pattern, a second allele Mr produces a pattern called restricted and a third allele md produces a pattern called dusky. In this allelic series, restricted is dominant over mallard and dusky, and mallard is dominant over dusky: Mr>M>Md. What are the phenotypes for the genotypes provided
MrM- restricted
MM-mallard
MdMd-dusky
In class we stated that traits have a dominant or recessive inheritance and not alleles. Why is this true and what are two examples of the levels a genotype many manifest as a phenotype.
Environment also plays a role
Expresivity and penetrance
XX with a copy of the SRY gene on an autosome
male
XO with a copy of the SRY gene on an autosome
male
XY with SRY deleted
female
XXYY with one copy of the SRY gene deleted
Male
XXY with the SRY gene deleted
Female
Genetic counselling is an educational process that provides the patients and their families information about the genetic condition and the mode of inheritance. Which of these modes of inheritance cannot skip a generation if one of the parents is affected
Autosomal Dominant
Why are adoption studies of twins useful for understanding the influence of genetics
the adoptive and biological parents environments are usually not the same
adoptive parents and biological parents are typically not related
A mother believes she has a chance to pass to her progeny a disease that has affected her. Her husband is unaffected and not a carrier. They have two sons. What proportion of her sons will inherit this disease that is known to be an X linked recessive trait
All
When attempting to map an allele to a trait of interest in multiple generations what grouping of individuals is most often used
pedigreed individuals
An unaffected male meets with a genetic counselor to ask if he has children with his wife whom is unaffected what proportion of his children will inherit a disorder seen in other family members that is known to be a Y linked trait
no sons and no daughters
Recombination rates vary and can be used to determine the distance and relative order of genes on a chromosome. Which of the following are true for the ratio of recombination rate relationship to various measures on the map
a) a recombination rate of 9=8 centimorgans
b)a recombination rate of 12=12 mapping units
c) a recombination rate of 5=10 centimorgans
d) a recombination rate of 21=10 mapping units
b)a recombination rate of 12=12 mapping units
Genome wide association studies (GWAS) locate genes that affect traits by examining the non-random association of a trait to genetic markers from across the genome. What is the term that defines the specific type of genetic marker used in GWAS approach
Single nucleotide polymorphisms (SNPs)
For dizygotic twins in adoption studies on the influence of genes and the environment in cases of adoptions it is assumed that the adopted individuals share this factor(s) with their biological parents
50% of the mothers genes
50% of the fathers genes
In a 3-point test cross to determine gene orde3r for the linked genes a,b, and c we need to start with which type of cross-over to determine gene order
double crossovers
Genetic mosaicism
individuals whose cells hold different genetic constitutions
Logarithm of odds
the probability of obtaining the observed results under a specified degree of recombination divided by the probability of the observed results under the assumption the genes are independently sorting
Chiasma
a point of contact between two homologous chromosomes during meiosis which results in a crossover event
Repulsion
each chromosome has one normal-type allele and one mutant allele
Haplotype
Group of genes inherited together from a single parent
Concordance
the percentage of twin pairs that both display the trait
Crossing over
the physical process of reciprocal exchange of chromosome segments at a corresponding positions along homologous chromosomes
Proband
the first person to report their families genetic history to a genetic counselor
Interference
The degree with which a single crossover can inhibit other crossover agents
Pedigree
a pictorial diagram of the genetic relationships among family members
For autosomal dominant traits there are multiple facts used to determine this mode of inheritance. List any two of these facts
doesn’t skip a generation
each gender is equally affected/equally transmit the trait
T/F
In a 3-point test cross double crossovers are more frequent than single crossovers between genes
True
T/F
A single crossover will switch the alleles on a single chromosome but another crossover can reverse the effects of the first thus restoring the original parental allele combination
True
T/F
If the number of observed progeny shows a 50% recombination frequency for a test of linkage between two genes we can conclude the genes are linked
False
T/F
If a testcross is performed and you determine the genes are not linked the ratio of progeny phenotypes should be 1:1:1:1
True
T/F
When performing a 3-point test cross, moving one of the three genes to the end will allow you to order all three
False
T/F
In complete linkage, assuming coupling, observed progenies are 50% nonrecombinants and 50% recombinants
False
T/F
Alfred Sturtevant was the first to define the chromosome theory of inheritance
F
T/F
For single crossovers, the frequency of recombinant gametes is half the frequency of crossing over because each crossover takes place between only two of the four chromatids of a homologous pair
True
T/F
The coefficient of coincidence is used to estimate interference
True
T/F
For independent assortment >50% of progeny will be parentals and <50% non-parentals
True
