LS7B week 1:

bivalent

a four-standed chromosomal structure formed in prophase 1

neutral mutation

a mutation that has no effect on survival or reproduction (many mutations are neutral bc they occur in noncoding DNA)

non-sister chromatids

chromatids of different members of a pair of homologous chromosomes; although they carry the same complement of genes, they are not genetically identical

Refer to Animation: Somatic Mutations in Cancer. Mutations arise in which order in the colon cancer example shown in the animation? a)Ras, APC, p53 b)p53, Ras, APC c)APC, p53, Ras d)APC, Ras, p53

d)APC, Ras, p53

spontaneous mutations

occurring in the absence of any assignable cause; most mutations are spontaneous

P1 generation

parental generation in a series of crosses

Meiosis

reductional division; the first stage of meiotic cell division, in which the number of chromosomes is halved

Prophase 1

the beginning of meiosis 1, marked by the visible manifestation of chromosome condensation

Allelles

the different forms of a gene corresponding to different DNA sequences in each different form

Phenotype

the expressed traits of an organism (physical, behavioral , or biochemical) phenotype results from an interaction between the genotype and the environment

what is the most common mutation

nucleotide substitution mutation

reciprocal crosses

A cross in which the female and male parents are interchanged.

chiasma

A crosslike structure within a bivalent constituting a physical manifestation of crossing over.

meiotic cell division

A form of cell division that includes only one round of DNA replication but two rounds of nuclear division; meiotic cell division makes sexual reproduction possible.

germ-line mutation

A mutation that occurs in eggs and sperm or in the cells that give rise to these reproductive cells and therefore is passed on to the next generation. researchers study # of mutations per genome per generation

somatic cells

A nonreproductive cell, the most common type of cell in the body of a multicellular organism.

hotspots

A site in the genome that is especially mutable.

Genotype

An organism's genetic makeup, or allele combinations.

true-breeding

Describes a trait whose physical appearance in each successive generation is identical to that in the previous one.

Alleles

Different forms of a gene corresponding to different DNA sequences (polymorphisms) in each different form

Meiosis II

Equational division, the second stage of meiotic cell division, in which the number of chromosomes is unchanged.

F1 generation

The first filial, or offspring, generation.

Synapsis

The gene-for-gene pairing of homologous chromosomes in prophase I of meiosis.

crossover

The physical breakage, exchange of parts, and reunion between non-sister chromatids.

germ cells

The reproductive cells that produce sperm or eggs and the cells that give rise to them. (haploid gametes and the diploid cells that give rise to them)

somatic mutation

a mutation that occurs in somatic cells somatic mutations are not transferred to future generations they are transmitted to daughter cells in mitotic cell divisions -> so it also affects the cells the descend from it researchers study the rate of mutations per nucleotide per replication

According to the figure shown, the average number of new mutations that occur across an entire human genome in one generation is approximately _____ times higher than in nematodes. a)100 b)2 c)10 d)1000 e)10,000

a)100

Refer to Animation: Somatic Mutations in Cancer. What effect does each successive mutation have on the colon cells in the example? a)It causes them to divide more rapidly than normal cells. b)It causes them to leave the colon and spread to other tissues. c)It causes them to become non-colon cells d)In causes them to become larger and expand in the colon.

a)It causes them to divide more rapidly than normal cells.

Refer to Animation: Somatic Mutations in Cancer. How do mutations arise? a)Mutations arise randomly and independent of other mutations in the cell. b)Mutations in cancer cells arise because they need to divide faster. c)Mutations arise in a specific sequence where a mutation in one gene directly leads to a mutation in a specific second gene. d)Mutations arise simultaneously, where whole sets of mutations occur in a single event.

a)Mutations arise randomly and independent of other mutations in the cell.

Somatic mutations are important to the evolutionary process; most cancers result from somatic mutations. a)false b)true

a)false

Refer to Animation: Somatic Mutations in Cancer. How do most cancers arise? a)from a series of mutations that arise in the descendants of a single somatic cell b)from multiple mutations arising simultaneously in a single cell c)from a single mutation arising simultaneously in a cluster of cells d)from mutations arising in a single cell that are then transmitted to other cells in the body

a)from a series of mutations that arise in the descendants of a single somatic cell

In genetic crosses, the symbol Aa refers to a: a)genotype. b)phenotype. c)morphotype. d)holotype e).archetype.

a)genotype.

Sites in the genome that are more susceptible to mutations than others are called: a)hotspots. b)genes. c)mutation spots. d)risk factors. e)noncoding DNA.

a)hotspots.

Polymorphism

any genetic difference among individuals that is present in multiple individuals in a population

genetic risk factor

any mutation that increases the risk of disease in an individual (does not cause the disease but rather increases the likelihood of it occurring)

Which of the statements concerning cancer and mutations is correct? a)Cancer can only occur with a mutation in a somatic cell. b)Usually multiple mutations are required in different genes to cause cancer. c)Usually a single mutation is all that is required to cause cancer. d)None of the other answer options is correct. e)Cancer can only occur with a mutation in a germ cell.

b)Usually multiple mutations are required in different genes to cause cancer.

True-breeding plants are typically heterozygous for most genes. a)true b)false

b)false

An allele is: a)None of the other answer options is correct. b)one of several forms of a gene. c)the particular combination of genes for a given trait in a given organism. d)the expression of a trait in an individual. e)the location of a gene in a chromosome.

b)one of several forms of a gene.

Huntington's disease is a devastating neurological disorder. If a child of an affected parent receives one copy of the Huntington allele, he or she will develop Huntington's disease. Thus, Huntington's disease is considered a _____ trait. a)reciprocal b)recessive c)dominant d)neutral

c)dominant

Refer to Animation: Somatic Mutations in Cancer. When p53 becomes mutant in cells already mutant for APC and Ras, what occurs? a)These cells remain benign. b)These cells expand their chromosome number to 53. c)These cells die d)These cells survive despite DNA damage and divide extremely rapidly.

d)These cells survive despite DNA damage and divide extremely rapidly.

The number of new mutations in genomes following a round of genome replication: a)is similar independent of genome size. b)None of the other answer options is correct c)generally decreases with larger genomes. d)generally increases with larger genomes. e)is highest in bacteria.

d)generally increases with larger genomes. Although the rate of mutation per nucleotide might be similar in different organisms, the bigger the organisms' genome, the higher the total number of mistakes that are left unrepaired.

The definition of mutation is "any heritable change in the genetic material." The qualifier "heritable" is necessary because: a)changes in the genetic material occur at random along the genome. b)changes in the genetic material occur without regard for the needs of the organism. c)most changes in the genetic material are harmful to the organism. d)most changes in the genetic material are repaired soon after they occur.

d)most changes in the genetic material are repaired soon after they occur.

Dominant

describes an allele or trait that is expressed in heterozygotes. only one dominant allele is needed to express the phenotype

Recessive

describes an allele or trait that is only expressed in homozygotes, and not expressed in heterozygotes. two recessive alleles are needed to express the phenotype

Homozygous

describes an individual who inherits an allele of the same type from each parent or a genotype in which both alleles for a given genre are of the same type

Heterozygous

describes an individual who inherits different types of alleles from the parents, or genotypes in which the two alleles for a given gene are different

A phenotype always refers to something that you can see with your eyes, like hair color or eye color. a)false b)true

false

Harmful mutations are always quickly weeded out of a population. a)true b)false

false

The observable characteristics of an organism constitute its genotype. a)false b)true

false

An organism that has two different alleles of a given gene has a(n) _____ genotype. a)homozygous b)heterozygous c)aneuploid d)heteromorphic e)dizygous

heterozygous

Hybridization

interbreeding between two different varieties or species of an organism

Mutations result from

mistakes in DNA replication or unrepaired damage to DNA

Prometaphase 1

the stage of meiosis 1 in which the nuclear envelope breaks down and meiotic spindles attach to kinetochores on chromosomes

Genotype-by-environment interaction means that genetic and environmental influences may interact or contribute to the phenotypic outcomes in unpredictable ways. a)true b)false

true Norms of reaction show how phenotype can change depending on environmental conditions.