Book Problems CH1-4 Flashcards
Describe Mendel’s conclusions about how traits are passed from generation to generation
A pair of factors control the expression of a trait. Each factor of the pair splits from each other during gamete formation.
What is the impact of recombinant DNA technology on genetics as we see the discipline today?
Gene cloning and recombinant DNA technology have enabled precise manipulation of genetic material. Allowing for improvements in agriculture and human health.
What is the chromosome theory of inheritance and how is it related to Mendel’s findings?
Chromosome theory of inheritance states thatinherited traits are controlled by genes. Both the chromosome theory of inheritance and Mendel’s findings are the same.
Define genotype and phenotype. Describe how they are related and how alleles fit into these.
Genotype - specific allelic or genetic makeup of an organism
Phenotype - observable features of the genotype
Alleles are gene variants, and have the potential to change a person’s phenotype.
Contrast chromosomes and genes.
Chromosome - molecule containing the organism’s genome
Gene - fundamental physical unit of heredity. Genes make up chromosomes.
How is genetic information encoded in a DNA molecule?
Through genes. Consist of linear sequences of nucleotides, exerting their influence by producing proteins via transcription and translation.
Describe the central dogma of molecular genetics and how it serves as the basis of modern genetics.
Central dogma is the relationship of DNA, RNA, and proteins. Process of transcription and translation link these together and form relationships between these.
How many different proteins, each with a unique amino acid sequence, can be constructed that have a length of 5 amino acids?
20^5 power
What are some of the impacts of biotechnology on crop plants in the United States?
Herbecide-resistant crops are more prevalent in farmland. Over 75% of processed food in the U.S. contains GMOs.
Summarize the arguments FOR and AGAINST patenting GMOs
FOR: Needed in order to encourage innovation & make back the costs of discovery.
AGAINST: natural substances should not be privately owned. Once these patents are owned by a handful of companies, free enterprise will be limited.
How has the use of model organisms advanced our knowledge of the genes that control human diseases?
Since many genetic systems are highly conserved across phylogenetic lines, model organisms can be usefull in understanding genes that influence disease. What is learned by one organism can usually be applied to majority of organisms.
In an organism with a diploid number of 2n = 6, how many individual chromosomal structures will align on the metaphase plate during:
a) mitosis
b) meiosis I
c) meiosis II
Describe each configuration
a) 6 chromosome (“X”) structures
b) 3 tetrad (“XX”) structures
c) 3 chromosome (“X) structures
Disregarding crossing over, draw all possible alignment configurations that can occur during metaphase I for a 2n = 4 organism.
Should be 4 possible configurations.
How many different chromosome configurations can occur following meiosis I if 3 different pairs of chromosomes are present? (2n = 6)
8 configurations
* Think 2^n
Describe the composition of a meiotic tetrad during prophase I, assuming no crossover event has ocurred. What impact would a single crossover event have on this structure?
Describe: 4 chromatids existing as 2 pairs. These pairs are called sister chromatids and held together by a common centromere. One pair is maternally derived, the oter paternally.
Crossover: Exchanging a portion of a maternal and paternal chromatid. Causes a chiasma.
What role do the following cellular components play in the storage, expression, or transmission of genetic information?:
a) chromatin
b) nucleolus
c) ribosome
d) mitochondrion
e) centriole
f) centromere
a) genetic material responsible for maintaining hereditay information
b) Produces ribosomes
c) translates mRNA into protein
d) produces ATP and has mitochondrial DNA.
e) Helps migrations of chromosomes through spindle fibers in mitosis and meiosis
f) attachment point for sister chromatids and for spindle fibers
Discuss the concepts of homologous chromosomes, diploidy, and haploidy. What characteristics do 2 homologous chromosomes share?
Homologous chromosomes share many properties including: overall length, centromere position, banding patterns, and type/location of genes.
Diploidy - 2n - both members of the homologous pairs of chromosomes are present
Haploidy - 1n - ONE copy of each homologous chromosome
If 2 chromosomes of a species are the same length and have similar centromere placements and yet are NOT homologous, what is different about them?
They have different genetic content. This includes different loci and genes.
Describe the events that characterize each stage of mitosis
Prophase - Chromosomes condense and enter cytosol
Prometaphase - Spindle fibers form and attach to chromosomes
Metaphase - Chromosome lines up in the center
Anaphase - Sister chromatids are split apart by spindle fibers
Telophase - chromosomes reach end of the cell, new nuclei reform
Cytokinesis - Cell splits into 2
How are chromosomes named on the basis of their centromere placement?
Metacentric = middle
Submetacentric = slightly off the middle
Acrocentric = close to end
Telocentric = at end
Describe the phases of the cell cycle and the events that characterize each phase
G1 - Cell is born and grows
S1 - Cell copies its chromosomes, preparing to divide
G2 - Cell grows again in preparation to divide
Mitosis - Cell divides
G0 - Dormancy and stop growing/dividing
Define these terms:
a) synapsis
b) chiasmata
c) crossing over
d) sister chromatids
e) tetrads
a) Point-by-point pairing of homologous chromosomes during Prophase I
b) Plural of chiasma. Refers to WHERE the chromatids crossed over
c) Exchange of genetic material between chromatids
d) post-synthesis phase structures of replication chromosomes. Identical and attached to same centromere
e) Synapsed homologous chromosomes (composed of 4 chromatids)
Contrast the genetic content and the origin of sister VS nonsister chromatids during their earliest appearance in Prophase I. How might the genetic content of these change by the time tetrads have aligned at the equatorial plate during Metaphase I?
Sister chromatids have identical genetic content and come from the same chromosome. Nonsister chromatids are similar, but not identical due to them being from different parents.
Might change through independent assortment or crossing over.
Given the end results of the 2 types of division, why is it necessary for homologs to pair during meiosis and NOT desirable for them to pair during mitosis?
More difficult for genetically identical daughters to form from mitosis if homologous chromosomes are paired.
Contrast spermatogenesis and oogenesis. What is the significance of the formation of polar bodies?
Spermatogenesis: 4 sperm cells of equal size
Oogensis: 1 ovum and polar bodies
Polar bodies: Eliminate one half of the diploid chromosome set produced by meiosis.
Explain why meiosis leads to significant genetic variation while mitosis does not
Through independent assortment of chromosomes at Anaphase I, daughter cells may contain different sets of maternally & paternally derived chromosomes. Through crossing over, maternal and paternal chromosomes exhcnage segments which increases the likelihood that daughter cells are genetically unique.
A diploid cell contains three pairs of homologous chromosomes designated C1 and C2, M1 and M2, and S1 and S2. No crossing over occurs. What combinations of chromosomes are possible following both divisions of meiosis
C1, M1, S1
C1, M2, S2
C1, M1, S2
C1, M2, S1
C2, M1, S1
C2, M2, S1
C2, M1, S2
C2, M2, S2
What is the probability that, in an organism with a haploid number of 10, a sperm will be formed that contains all 10 chromosomes whose centromeres were derived from maternal homologs?
Probability that one-half of each tetrad will have a materal homolog: (1/2) ^10
Contrast the chromatin fiber with the mitotic chromosome. How are the 2 structures related?
Chromatin fibers repreent an intermediate level of packaging
Mitotic chromosomes represent the highest level of condensing.
Both structures are involved in DNA packaging and organization.
If one follows 50 primary oocytes in an animal through their various stages of oogenesis…
a) how many secondary oocytes would be formed?
b) How many first polar bodies would be formed?
c)How many ootids would be formed?
a) 50
b) 50
c) 50
If one follows 50 primary spermatocytes in an animal through their various stages of spermatogenesis…
a) how many secondary spermatocytes would be formed?
b) How many spermatids would be formed?
a) 100
b) 200
Albinism in humans is inherited as a simple recessive trait. For the following families, determine the genotype of the parents and offspring:
a. Two normal parents have 5 children, four normal and 1 albino
b. A normal male and an albino female have 6 children, all normal.
c.A normal male and an albino female have 6 children, 3 normal and 3 albino.
a. Aa x Aa = 1AA:3Aa:1aa
b. AA x aa = 6Aa
c. Aa x aa = 3Aa x 3aa
What advantages were provided by Mendel’s choice of the garden pea in his experiments?
Quick growth, easy hybridization, and easily observable traits
What is the basis for homology among chromosomes?
We receive 1 part of a pair of chromosomes from 2 parents, so these chromosomes are homologous. They share the genes, with potentially different alleles.
How many different types of gametes can be formed by individuals of the following genotypes: (a) AaBb, (b) AaBB, (c) AaBbCc, (d) AaBBcc, (e) AaBbcc, and (f) AaBbCcDdEe?
a) 4
b) 2
c) 6
d) 2
e) 4
f) 8
In assessing data that fell into two phenotypic classes, a geneticist observed values of 250:150. She decided to perform a analysis by using the following two different null hypotheses:
(a) the data fit a 3:1 ratio
(b) the data fit a 1:1 ratio.
Calculate the values for each hypothesis. What can be concluded about each hypothesis?
a) the null hypothesis should be rejected
b) the null hypothesis should also be rejected
In foxes, two alleles of a single gene, P and p, may result in lethality (PP), platinum coat (Pp), or silver coat (pp). a) What ratio is obtained when platinum foxes are interbred?
b) Is the P allele behaving dominantly or recessively in causing (a) lethality; (b) platinum coat color?
a. 2/3 platinum, 1/3 silver
b. recessive lethal allele , dominant coat color
List all possible genotypes for the A, B, AB, and O phenotypes. Is the mode of inheritance of the ABO blood types representative of dominance, recessiveness, or codominance?
AA, BB, AO, BO, AB, OO
Mode of inheritance depends on alleles present.
A or B are dominant to O, so O is recessive.
A and B are codominant to eachother.
A husband and wife have normal vision, although both of their fathers are red–green color-blind, an inherited X-linked recessive condition. What is the probability that their first child will be (a) a normal son, (b) a normal daughter, (c) a color-blind son, (d) a color-blind daughter?
a) 1/4
b 2/4
c) 1/4
d) 0/4
