BYUI Unit 2 Genetics Bio 181

what is the product of meiosis?

4 haploid cells

dihybrid

A cross between 2 true breeding parents that express different traits for 2 characteristics

metaphase plate

An imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located.

Autosome

Any chromosome that is not a sex chromosome

autosomes

Any chromosome that is not a sex chromosome

Okazaki fragments

DNA fragments that are synthesized in short stretches on the lagging strand

Heterozygous

Having two different alleles for a given gene on the homologous chromosome

Homozygous

Having two identical alleles for a given gene on the homologous chromosome

gametophyte

The multicellular haploid life cycle stage that produces gametes

Karyogram

a karyotype's photographic image

alternation of generations

a life-cycle type in which the diploid and haploid stages alternate

sporophyte

a multicellular diploid life cycle stage that produces haploid spores by meiosis

Meiosis

a nuclear division process that results in four haploid cells

reduction division

a nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus; meiosis I is a reduction division

linkage

a phenomenon in which alleles that are located in close proximity to each other on the same chromosome are more likely to be inherited together

somatic cell

all the cells of a multicellular organism except the gametes or reproductive cells

Aneuploid

an individual with an error in chromosome number; includes deletions and duplications of chromosome segments

euploid

an individual with the appropriate number of chromosomes for their species

Karyotype

an individual's chromosome number and appearance; includes the size, banding patterns, and centromere position

During which phase of meiosis are sister chromatids separated?

anaphase II

Epistasis

antagonistic interaction between genes such that one gene masks or interferes with the expression of another

recombination frequency

average number of crossovers between two alleles; observed as the number of nonparental types in a population of progeny

Interkinesis (Interphase II)

brief period of rest between meiosis I and meiosis II

lagging strand

bring up location, The Strand that is replicated in short fragments and away from the replication fork

diploid

cells containing 2 sets of chromosomes

Haploid

cells that contain a single set of chromosomes

single strand binding protein

during replication, protein that binds to the single stranded DNA; this helps in keeping the two strands of DNA apart so that they may serve as templates

Helicase

during replication, this enzyme helps to open up the DNA Helix by breaking the hydrogen bonds

Ligase

enzyme that catalyzes the formation of a phosphodiester linkage between the 3' OH and 5' phosphate ends of the DNA

Telomerase

enzyme that contains a catalytic part and an inbuilt RNA template; it functions to maintain telomeres at chromosome ends

Primase

enzyme that synthesizes the RNA primer; the primer is needed for DNA polymerase to start synthesis of a new DNA strand

Crossover

exchange of genetic material between non-sister chromatids resulting in chromosomes that incorporate genes from both parents of the organism

F1

first filial generation

Proofreading

function of DNA polymerase in which it read the newly added base before adding the next one

Allele

gene variations that arise by mutation and exist at the same relative locations on homologous chromosomes

law of independent assortment

genes do not influence each other with regard to sorting of alleles into gametes; every possible combination of alleles is equally likely to occur

spore

haploid cell that can produce a haploid multicellular organism or can fuse with another spore to form a diploid cell

Blending Theory of Inheritance

hypothetical inheritance pattern in which parental traits are blended together in the offspring to produce an intermediate physical appearance

Codominance

in a heterozygote, complete and simultaneous expression of both alleles for the same characteristic

incomplete dominance

in a heterozygote, expression of 2 contrasting alleles such that the individual displays an intermediate phenotype

law of dominance

in a heterozygote, one trait will conceal the presence of another trait for the same characteristic

polyploid

individual with an incorrect number of chromosome sets

continuous variation

inheritance pattern in which a character shows a range of trait values with small gradations rather than large gaps between them

dominant lethal

inheritance pattern in which an allele is lethal both in the homozygote and the heterozygote; this allele can only be transmitted if the lethality phenotype occurs after reproductive age

Discontinuous variation

inheritance pattern in which traits are distinct and are transmitted independently of one another

pericentric

inversion that involves the centromere

paracentric

inversion that occurs outside of the centromere

sexual reproduction

involves the production by parents of 2 haploid cells and the fusion of these to form a single, genetically recombined diploid self creates a genetically unique organism

homologous chromosomes

matched pairs containing the same genes in identical locations along their lengths.

4 gametes are produced with with the haploid number of chromosomes. This statement is true for....

meiosis II only

In the fungi life cycle...

meiosis occurs followed by mitosis then followed by fertilization

During which phase of meiosis do homologous chromosomes align at the center of the cell and independent assortment occurs?

metaphase I

point mutation

mutation that affects a single base

silent mutation

mutation that is not expressed

induced mutation

mutation that results from exposure to chemicals or environmental agents

spontaneous mutation

mutation that takes place in the cells as a result of chemical reactions taking place naturally without exposure to any external agent

Monosomy

otherwise diploid genotype in which one chromosome is missing.

Trisomy

otherwise diploid genotype in which one entire chromosome is duplicated

Law of Segregation

paired unit factors (i.e., genes) segregate equally into gametes such that offspring have an equal likelihood of inheriting any combination of factors

In which sexual life cycle does mitosis occur immediately following fertilization?

plant and animal

homologous recombination

process by which homologous chromosomes undergo reciprocal physical exchanges at their arms, also crossing over

Translocation

process by which one segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome

nonparental (recombinant) type

progeny resulting from homologous recombination that exhibits a different allele combination compared with its parents

parental types

progeny that exhibits the same allelic combination as its parents

During which phase of meiosis does crossing over occur to produce genetic diversity?

prophase I

the symptonemal complex forms during what stage of meiosis?

prophase I

recombination nodules

protein assemblies formed on the synaptonemal complex that mark the points of crossover events and mediate the multistep process of genetic recombination between non-sister chromatids

synaptonemal complex

protein lattice that forms between homologous chromosomes during prophase I, supporting crossover

cohesin

proteins that form a complex that seals sister chromatids together at their centimetres until anaphase

centiMorgan(cM)

relative distance that corresponds to a 0,01 recombination frequency

sliding clamp

ring shaped protein that holds the DNA polymerase on the DNA strand

F2

second filial generation

primer

short stretch of nucleotides that is required to initiate replication; in the case of replication, the primer has are in a nucleotide

germ cells

specialized cell line that produces gametes, such as sperm and egg

leading strand

strand that is synthesized continuously in the 5'-3' direction, which is synthesized in the direction of the replication fork

Electrophoresis

technique used to separate DNA fragments according to size

The cleavage furrow forms and 4 haploid cells are formed. This occurs during....

telophase of meiosis II

telomere

the DNA at the end of linear chromosomes

X inactivation

the condensation of X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose

chromosome inversion

the detachment, 180° rotation, and reinsertion of a chromosome arm

Nondisjunction

the failure of synapsed homologs to completely separate and migrate to separate poles during the first cell division of meiosis

Meiosis I

the first round of meiotic cell division; referred to as reduction division because the ploidy level is reduced from diploid to haploid

synapsis

the formation of a close association between homologous chromosomes during prophase I

Cytokinesis

the physical separation of the cytoplasmic components into 2 daughter cells occurs without reformation of the nuclei

hemizygous

the presence of only one allele for a characteristic, as in X-linkage; hemizygosity makes descriptions of dominance and recessiveness irrelevant

Hybridization

the process of mating two individuals that differ, with the goal of achieving a certain characteristic in their offspring

Meiosis II

the second round of meiotic cell division following meiosis I; sister chromatids are separated from each other, and the result is four unique haploid cells

life cycle

the sequence of events in the development of an organism and the production of cells that produce offspring

chiasmata (chiasma)

the structure that forms at the cross over points after genetic material is exchanged

Genotype

the underlying genetic makeup, consisting of both physically visible and non-expressed alleles, of an organism

The chromosomal theory of inheritance

theory proposing that chromosomes are the vehicles of genes and that their behavior during meiosis is the physical basis of the inheritance patterns that Mendel observed

Dominant

trait which confers the same physical appearance whether an individual has 2 copies of the trait or one copy of the dominant trait and one copy of the recessive trait

tetrad

two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase I

nucleotide excision repair

type of DNA repair mechanism in which the wrong base, along with a few nucleotides upstream or Downstream, are removed

mismatch repair

type of repair mechanism in which mismatched bases are removed after replication

asexual reproduction

type of reproduction where unicellular organisms and a few multicellular organisms can produce genetically identical clones of themselves

Fertilization

union of 2 haploid cells from 2 individual organisms

Mutation

variation in the nucleotide sequence of a genome

replication fork

y shaped structure formed during initiation of replication

in th animal sexual life cycles, meiosis produces gametes, and fertilization produces what?

zygotes