BIO EXAM 6 CH 13, 14, 15

heredity

The transmission of genetic traits from parents to offspring, involving the passing of genes through generations.

variation

The differences in genetic traits among individuals within a population

genetics

The study of heredity and the variation of inherited characteristics in living organisms.

genes

The basic units of heredity made up of DNA, responsible for the transmission of traits from parents to offspring.

gametes

the vehicles that transmit genes from one generation to the next

somatic cells

Any body cell that is not a sperm or egg cell

locus

a gene’s specific location along the length of a chromosome

asexual reproduction

the process by which offspring are produced from a single parent without the involvement of gametes, resulting in genetically identical individuals.

clone

an individual or group of individuals that are genetically identical to the parent

sexual reproduction

the process by which offspring are produced from the fusion of gametes from two parents, resulting in genetically diverse individuals.

life cycle

the generation-to-generation sequences of stages in the reproductive history of an organism from conception to production

karyotype

a visual representation of the chromosome composition of an individual

homologous chromosomes

two chromosomes of a pair that have the same length, centromere position, and staining pattern

autosomes

non-sex chromosomes that determine most of an organism's traits and characteristics

diploid cell

a cell that contains two complete sets of chromosomes, one from each parent

haploid cells

cells that contain only one set of chromosomes, typically found in gametes such as sperm and eggs.

fertilization

the union of gametes

zygote

a fertilized egg

meiosis

the process of cell division that reduces the chromosome number by half, producing four haploid cells from one diploid cell.

germ cells

the reproductive cells that give rise to gametes, specifically sperm and eggs.

alternation of generations

is a life cycle in which organisms alternate between haploid and diploid phases

allele

a variant form of a gene that governs a specific trait, located on a chromosome.

prophase I

is the first stage of meiosis where homologous chromosomes undergo synapsis and crossing over occurs.

crossing over

the DNA molecules of non sister chromatids are broken by proteins and are rejoined together

chiasmata

the physical X-shaped point of contact between two non-sister chromatids

metaphase I

is the stage of meiosis I where homologous chromosome pairs align in the center of the cell, known as the metaphase plate, before being pulled apart.

anaphase I

is the stage of meiosis I where homologous chromosomes separate and move to opposite poles of the cell.

telophase I and cytokinesis

are the final stages of meiosis I where the chromosomes reach the poles, the nuclear membranes reform, and the cell divides into two daughter cells.

prophase II

is the stage of meiosis II where the nuclear envelope breaks down again, and the spindle apparatus forms to prepare for the next division.

metaphase II

is the stage of meiosis II where chromosomes align at the cell's equatorial plate, preparing for separation.

anaphase II

is the stage of meiosis II where sister chromatids are pulled apart toward opposite poles of the cell.

telophase and cytokinesis II

is the final stage of meiosis II where the separated sister chromatids reach the poles, nuclear envelopes reform, and the cell divides into two haploid cells.

synaptonemal complex

the zipper-like structure that holds one homolog tightly to the other

synapsis

lengthwise pairing of homologous chromosomes during prophase I

independent assortment

is the random distribution of homologous chromosome pairs during meiosis, leading to genetic variation in gametes.

recombinant chromosomes

individual chromosomes that carry genes from two different parents due to crossing over during meiosis.

character

a heritable feature that varies among individuals

trait

a specific variant of a character

true-breeding

organisms that, when crossed, always produce offspring with the same phenotype.

hybridization

the process of crossing two true-breeding varieties to produce offspring with mixed traits.

P generation

the true-breeding parent

F1 generation

hybrid offspring

F2 generation

the offspring resulting from the cross of two F1 hybrids.

dominant allele

determines the organism’s appearance

recessive allele

has no noticeable effect on the organism’s appearance

law of segregation

The principle stating that alleles for a trait separate during gamete formation, ensuring that each gamete carries only one allele for each gene.

Punnett square

A diagram that predicts the genotype and phenotype ratios of offspring from a genetic cross by considering all possible combinations of alleles from the parents.

homozygote

An organism that carries two identical alleles for a particular trait.

heterozygote

An organism that carries two different alleles for a particular trait.

phenotype

an organism’s observable traits g

genotype

an organism’s genetic makeup

testcross

the breeding of an unknown genotype with a homozygous recessive individual to determine the unknown genotype.

monohybrids

individuals that are heterozygous for one particular gene of interest

dihybrids

individuals heterozygous for the two characters being followed in the cross

law of independent assortment

two or more genes assort independently of one another during gamete formation, meaning the inheritance of one trait does not influence the inheritance of another.

multiplication rule

The rule used to determine the probability of two or more independent events occurring simultaneously

addition rule

the probability that any one of two or more mutually exclusive events will occur is calculated by adding their individual probabilities

complete dominance

is a type of inheritance where one allele is completely dominant over another

incomplete dominance

is a type of inheritance in which neither allele is completely dominant over the other

codominance

is a type of inheritance where both alleles in a heterozygous organism are fully expressed

Tay-Sachs disease

an inherited disorder where brain cells cannot metabolize lipids

pleiotropy

a gene having multiple phenotypic effects

epistasis

the phenotypic expression of a gene at one locus alters that of a gene at another locus

quantitative characters

characters that vary in the population in gradations along a continuum

polygenic inheritance

a trait controlled by two or more genes, resulting in a continuous range of phenotypes.

multifactorial