unit 5 - heredity

diploid

2 sets of chromosomes, cell contains one set each parent

what is a diploid represented by?

2n

haploid

one set of chromosomes

what is a haploid represented by?

n

two haploid gamete cells come together to make a

diploid cell

meiosis results in daughter cells with

half the number of chromosomes as parent cell

meiosis involves

two rounds of steps

prophase 1

nuclear envelope begins to disappear, fibers begin to form, DNA coils into visible chromosomes

metaphase 1

fibers align pairs across center of cell

anaphase 1

fibers separate chromosome pairs, chromosomes migrate to opposite sides of cell

telophase 1

nuclear envelope reappears + establishes two separate nuclei

after telophase 1, how many chromosomes does each nucleus have?

contains only one double chromosome from each pair

prophase 2

nuclear envelope disappears, fibers begin to form

metaphase 2

fibers align double chromosomes across center of cell

anaphase 2

fibers separate sister chromatids, chromatids migrate to opposite sides of cell

telophase 2

nuclear envelope reappears + establishes separate nuclei, chromosomes begin to uncoil

how many chromosomes are in each nucleus after telophase 2?

each nucleus contains single chromosomes

what does mitosis produce?

two daughter cells that are genetically identical to parent cell

what does meiosis produce?

two daughter cells that are genetically different to parent cell

what does crossing over increase?

genetic diversity among gametes

when does crossing over occur?

in prophase 1

crossing over

nonsister chromatids of double homologous chromosomes exchange segments

homologous chromosomes

carry info for same genes, one from each parent

what does crossing over result in

recombinant chromatids

random assortment of chromosomes serves to

increase variation

random assortment

order of homologous pairs during metaphase 1, affecting which chromosomes end up in each gamete

fertilization of gametes serves to

increase variation

fertilization of gametes

info from each parent is contributed to fertilized egg, one gamete from each parent fuse together (diploid offspring)

nucleic acids are carriers of what?

genetic information

genetic info is transferred during

cell division

major features of genetic code are shared by

all living systems

all organisms use nucleic acids to

store and transmit genetic info

all living systems have

ribosomes

ribosomes are used to

synthesize proteins based on nucleic acid sequences

shared features support what concept?

common ancestry

mendel’s laws

describe inheritance of genes + traits on different chromosomes

gene

unit of heredity coding for a trait

trait

genetically determined characteristic of an organism

allele

specific variation of a gene

what are alleles represented by

letters (ex. A, a)

dominant allele

always shows in phenotype (uppercase letter)

recessive allele

only shows in phenotype when dominant allele has NOT been inherited

genotype

combination of inherited alleles

homozygous

genotype containing two of the same alleles

heterozygous

genotype containing two different alleles

phenotype

physical result or expression of genotype

law of segregation

when chromosomes separate into daughter cells, alleles for each trait also separate (chromosomes carry alleles + homologous chromosomes carry alleles for same trait)

separation of alleles allows for

genetic variation among gametes

law of independent assortment

two or more genes assort independently of each other, one trait is not automatically inherited with another trait

monohybrid cross

examination of how one trait is inherited

dihybrid cross

examination of how two traits are inherited

pedigree

visual representation tracing history of trait through familial generation

circles in pedigree

biological femiles

squares in pedigree

biological males

autosomal

non sex chromosomes

autosomal dominant traits

show pattern of affected offspring with affected parents

autosomal recessive traits

show pattern of affected offspring with unaffected parents

hypothesis testing

used to reject or fail statistical hypothesis

what is hypothesis testing helpful?

helps to determine if differences in numerical data are due to independent variables or due to chance

null hypothesis

states there is NO relationship/difference between two groups of data

alternative hypothesis

states observed results ARE DUE to a nonrandom cause

chi-square goodness-of-fit test

used to determine if there is a significant relationship between two groups of data

if chi-square value is less than critical value

fail to reject null hypothesis

if chi square value is greater than critical value

reject null hypothesis

linked genes

genes that are adjacent to one another on the same chromosome + are inherited together

sex-linked traits

traits that are determined by genes located on sex chromosomes

map distance

tells you how close together a pair of linked genes is

how is map distance determined?

by how frequently a pair of genes participates in a single crossover event

in humans, how many X chromosomes do females have?

2 X chromosomes

in humans, how many X chromosomes do males have?

one X chromosome, and one Y chromosomes

Y chromosomes carry very little

genetic info

most sex-linked alleles are carried on

X chromosome

females can be considered _____ of a recessive sex-linked allele

carriers

males are more likely to have phenotypes associated with

recessive sex-linked alleles

many traits are a product of

multiple genes

mitochondria are transmitted to

egg

mitochondrial traits are

maternally inherited

environmental factors can influence

gene expression

phenotypic plasticity

ability of one genotype to produce more than one phenotype

what results in genetic variation?

Segregation, independent assortment, and random fertilization

nondisjunction

failure of chromosomes to fully separate during formation of gametes