Final Exam: CH 2, 3, 4, 5, 8 ,10, 14, 15, 16, 19, 24, 25, 27, 29

Question 1

Describe Mendel’s experiments and his laws

Answer 1

Experiments: Working with garden pea plants, Mendel found that crosses between parents that differed for one trait produced F1 offspring that all expressed one parent’s traits. The traits that were visible in the F1 generation are referred to as dominant, and traits that disappear in the F1 generation are described as recessive. When the F1 plants in Mendel’s experiment were self-crossed, the F2 offspring exhibited the dominant trait or the recessive trait in a 3:1 ratio, confirming that the recessive trait had been transmitted faithfully from the original P parent. Reciprocal crosses generated identical F1 and F2 offspring ratios. By examining sample sizes, Mendel showed that traits were inherited as independent events.
Laws: independent assortment (genes for different traits are sorted separately from another so inheritance of one trait is not dependent on another) and segregation (each inherited trait is defined by a gene pair and offspring randomly inherit one genetic allele from each parent)

Question 2

Monohybrid

Answer 2

Genetic cross between homozygous individuals with different alleles for a single gene

Question 3

Dihybrid

Answer 3

A genetic cross between individuals with different alleles fro two gene loci of interest

Question 4

Test cross

Answer 4

A cross between two true-breeding individuals for a given trait to establish what the genotype for the phenotypically dominant one is (basically if its is heterozygous or homozygous)

Question 5

Genotype

Answer 5

An organisms genetic info (ex: AA genotype)

Question 6

Phenotype

Answer 6

Set of observable of physical traits (ex: pink flower color)

Question 7

Dominant

Answer 7

The allele will be expressed if it is present and cover up the recessive allele, whether heterozygous or homozygous, often represented with a capital letter (ex: HH or Hh)

Question 8

Recessive

Answer 8

The allele will only be expressed if both copies are present, aka absence of the dominant allele, represented with lowercase letters (ex: hh)

Question 9

Heterozygote

Answer 9

Having copies of the dominant and recessive allele and therefore expressing the dominant phenotype (ex: Hh)

Question 10

Homozygote

Answer 10

Carrying two identical alleles (ex: HH or hh)

Question 11

Sister Chromatid vs. Homologous Chromosome

Answer 11

Sister chromatid: made up of either maternal or paternal chromosome, contain identical gene sequence EXCEPT in chromosomal crossover, formed during DNA replication of S phase of interphase, joined together by centromere, composed of single DNA strand, separated from the centromere during anaphase II of meiosis II and the anaphase of mitosis
Homologous chromosome: made up of both maternal and paternal chromosomes, may contain different or same alleles of the same gene, appear in metaphase 1 of meiosis, do not stick together, composed of 4 DNA strands, segregated in anaphase 1 of meiosis

Question 12

Define different types of dominance

Answer 12

Complete: when dominant allele is present and completely masks the recessive allele
Incomplete: neither allele is dominant, instead the heterozygote is an intermediate between the two phenotypes
Codominance: both traits are equally expressed in heterozygotes

Question 13

Epistasis vs Pleiotropy

Answer 13

Epistasis: when a gene at one locus influences the phenotypic expression of a gene at another locus (single trait, taking place between 2 or more genes)
Pleiotropy: when a single gene contributes to multiple traits (multiple phenotypic traits, a single gene)

Question 14

What are the 3 types of sex linkage

Answer 14

Sex limited: traits only visible within one sex (ex: barred coloring in chickens is only visible in roosters)
Sex linked: traits more likely to be visible in males, as females have a second X-chromosome to counteract the recessive trait (ex: color blindness)
Sex influenced: autosomal traits influenced by sex, it takes only one allele in men and two in women to be shown (ex: baldness)

Question 15

Epigenetics

Answer 15

Modifications to DNA that regulates whether genes are turned on or off, attached to DNA but doesn’t change the sequence

Question 16

Maternal Effect

Answer 16

Phenotypes of offspring are influenced by the genotype of the mother (ex: Lymnaea peregra (water snails) are arranged in either dextral or sinsitral directions and in a cross btwn an RR male and rr female, the F1 was all showing the recessive sinistral phenotype)

Question 17

Recombinant

Answer 17

A cell or offspring that carries a new combination of alleles or traits due to crossing over or the independent assortment of chromosomes

Question 18

Parental

Answer 18

A cell or offspring with the same combinations of alleles found in their parents chromosomes

Question 19

Chromosome rearrangements

Answer 19

Deletion: segment is missing
Duplication: section of a chromosome is repeated more than once within a chromosome
Inversion: a change in the direction of the genetic material along a single chromosome
Translocation: one segment of a chromosome becomes attached to a different chromosome or a different part of the same chromosome; reciprocal translocation is the same with two different chromosomes exchanging pieces

Question 20

Centromere

Answer 20

A segment that provides an attachment site for the kinetochore, where chromatids join, ensures proper segregation of chromosomes to daughter cells in mitosis and meiosis

Question 21

Telomere

Answer 21

Specialized repeated sequences found at the ends of eukaryotic chromosomes, prevent translocations and chromosome shortening

Question 22

Aneuploidy

Answer 22

A variation in chromosome number such that the total number of chromosomes is NOT an exact multiple of a set (ex: fruit flies normally have 8 chromosomes bc they’re diploid with 4 chromosomes/set, an abnormal fly could be aneuploid with 9 chromosomes if it had 3 copies of chromosome 2)

Question 23

Euploidy

Answer 23

The chromosome number is an exact multiple of a chromosome set (ex: fruit flies have a single set of 4 chromosomes, and theyre diploid with 2 sets of chromosomes, so they’re euploid bc 8/4=2 sets)

Question 24

Level 1 of chromosome compaction in eukaryotes

Answer 24

Stretches of DNA dbl helix warp around an octamer of histones alone the entire chromosome, making chromatin. The beadlike, histone DNA complex is a nucleosome. 2nm diameter dbl helix—>10nm diameter beads

Question 25

Level 3 of chromosome compaction in eukaryotes

Answer 25

A variety of fibrous proteins packs the chromatin into loop domains, ensuring each chromosome in a non-dividing cell is in a specific region called chromosome territory

Question 26

Level 2 of chromosome compaction in eukaryote

Answer 26

Linker DNA (connects nucleosomes) and nucleosomes are coiled into 30nm chromatin fiber, supercoiling.

Question 27

Histone

Answer 27

A group of proteins involved in forming the Nucleosome, the repeating structural unit within eukaryotic chromatin

Question 28

Nucleosome

Answer 28

A double stranded segment of DNA wrapped around an octamer of histones

Question 29

30nm fiber

Answer 29

A compact structure of associated Nucleosome units that is 30nm in diameter,

Question 30

Role of nucleus in compaction

Answer 30

Where it all has to fit, all chromosomes are made to fit in here at 2-4 micrometers in diameter

Question 31

Activators of gene regulation

Answer 31

Regulatory protein that binds to DNA and increases rate of transcription

Question 32

Repressors of gene regulation

Answer 32

Regulatory protein that binds to DNA and inhibits transcription

Question 33

Effectors of gene regulation

Answer 33

A small molecule that binds to the regulatory protein to govern its activity (ex: lactose binds with the regulatory protein LacR in E.Coli to control transcription of the LacZ gene)

Question 34

Lac operon

Answer 34

-DNA sequences in lac operon
1. CAP site: recognized by activator protein CAP
2. Lac promoter (lacP)
3. operator site (lacO): provides binding site for lac repressor
4. lacZ: encodes beta-galactosidase which cleaves lactose into glucose and galactose and allolactose (side rxn)
5. lacY: encodes lactose permease, membrane protein needed for active transport of lactose into cytoplasm of bacterium
6. lacA: encodes galactoside transacetylase, an enzyme that covalently modifies lactose and its analogs by attaching hydrophobic acetyl groups
7. Terminator
-Regulation
1. Lac repressor binds to lac operator and prevents RNA polymerase from transcribing lacZ/Y/A ; reversible and in absence of allolactase the repressor is usually bound to the operator site.

Question 35

Translation regulation

Answer 35

Controls levels of protein synthesized from mRNA.

Question 36

Post-translational regulation

Question 37

Transcription factor

Question 38

Why is gene regulation more complex in eukaryotes

Question 39

Motif

Question 40

Allosteric inhibition

Question 41

Upregulation and downregulation

Question 42

What is methylation? How does it effect gene expression through epigenetics?

Question 43

Cis and trans epigenetic factors

Question 44

Silent mutation

Question 45

Missense mutation

Question 46

Nonsense mutation

Question 47

Substitution mutation

Question 48

Frameshift mutation

Question 49

Intergenetic and intragenetic suppressor mutations

Question 50

Level 1 of chromosome compaction in eukaryotes