Unit 5 - Heredity

the storage and transmission of genetic information from one generation to the next occurs through meosis

genetics

genetics

study of hereditary variation

heredity

transmission of traits from one gen to the next

asexual

single individual, no fusion of gametes, clones, mutations are the only source of variation, mitosis

sexual

two parents, offspring are unique combinations of genes from parents, genetically varied from parents and siblings, meosis

homologous chromosome

a pair of chromosomes that carry the same genetic information and are identical

karyotypes

display of chromosome pairs ordered by size and length

somatic cells

diploid (2n)

two completed sets of each chromosome

gametic cells

haploid (n)

one set of each chromosome

autosomes

chromosomes that do not determine sex

sex chromosomes

X and Y; determine sex

life cycle

the sequence of stages in the reproductive history of an organism from conception to its own reproduction; fertilization and meiosis alternate

meiosis

process that creates haploid gametes cells in sexually reproducing diploid organisms

2 divisions, 4 haploid daughter cells, genetically unique

Interphase

G1, S, and G2

Prophase I

homologous chromosomes pair up to form tetrads with unique combinations of DNA

Metaphase I

independent orientation tetrads line up at the middle

Anaphase I

pairs of homologous chromosomes seperate while sister chromatids still attached

Telophase I and Cytokinesis

nuclei and cytoplasm divide to make two daughter cells with haploid set’s in each

Prophase II

no chromosomes cross over but spindle fibers form

Metaphase II

chromosomes line up at the metaphase plate and are still unique

Anaphase II

sister chromatids separate and move towards opposite poles

Telophase II and Cythokinesis

4 haploid cells are created, nuclei reappears, and each daughter cell is genetically unique

Gregor Mendel

Austrian monk who experimented on pea plants and discovered the basic principles of heredity

true-breeding

organisms that produce offspring of the same variety over many generations of self pollination

P generation

true-breeding parental generation

F1 generation

first filial hybrid offspring of P generation

all hybrids

F2 generation

second filial offspring of the G1 generation

always results in a 3:1 ratio

punnett squares

disgrams used to predict the allel combinations of offspring form a cross with known genetic compositions

homozygous

organism that has a pair of identical alleles for a character

AA

heterozygous

organism has two different alleles for gene

genotype

genetic makeup (alleles) of an organism

phenotype

organism’s appearance, which is determined by the genotype

testcross

help determine if dominant trait is homozygous or heterozygous

law of segregation

each gene separates from its corresponding allele so that each reproductive cell only contains one allele

law of independent assortment

genes for one trait are not inherited with genes for another trait; only applies to those located on different chromosomes

alleles

alternate versions of gene

monohybrid crosses

cross between true-breeding plants that produce F1 hybrids

dihybrid crosses

cross between true-breeding for two traits that produce F1 dihybrids

9:3:3:1

genotype

the genetic makeup and alleles

phenotype

appearance determined by the genotype

multiplication rule

the probability that two or more independent events will occur together in some specific combination

addition rule

the probability that two or more mutually exclusive events will occur

pedigree

family trees that give a visual of inheritance patterns of particular traits

non-Mendelian Genetics

varying degrees of dominance; many traits produced through many genes; some are on sex chromosomes

incomplete dominance

neither allele is fully dominant and creates a mix

red and white —> pink

codominance

two allele that affect phenotype are post expressed

AB blood type

multiple alleles

genes that exist in forms with more than two alleles

epistasis

a phenotype expression of a gene at one locus affects a gene at another locus

polygenic inheritance

effect of two or more genes acting on a single phenotype

sex-linked genes

genes located on either to X or Y chromosomes

genetic recombination

production of offspring with a new combination of genes from parents

parental types

offspring with the parental phenotype

recombinants

offspring with phenotypes that are different from the parents

linked genes

genes located near each other on the same chromosome that tend to be inherited together

linkage map

genetic map based on recombination frequencies and distance is expressed by map units

chi-square test

form of statistical analysis to compare actual data to expected results

nondisjunction

chromosomes fail to seperate properly in meiosis I or II

down syndrome

extra 21 chromosome

turner syndrome

one X chromosome is missing or partially missing in females

cri du chat

piece of chromosomes 5 is missing

klinefelter syndrome

two X and one Y chromosomes

digeorge syndrome

deletion of section on chromosome 22