BIO EXAM 3 REAL ONE

Meiosis

A process that creates haploid gametes from diploid cells, mixing DNA from two individuals.

Somatic Cells

Body cells that undergo mitosis and are not involved in sexual reproduction.

Gametes

Reproductive cells (spermatozoa in males and ova in females) formed through meiosis.

Anisogamous

Referring to gametes that are morphologically distinct between sexes.

Ploidy

The number of copies of each chromosome in a cell; can be haploid (1), diploid (2), triploid (3), tetraploid (4), etc.

Crossing Over

The process during meiosis in which homologous chromosomes exchange genetic material.

Genetic Recombination

The exchange of genes between chromosomes, resulting in a new combination of alleles.

Homologous Chromosomes

Chromosome pairs, one from each parent, that are similar in shape, size, and genetic content.

Zygote

The fertilized egg that is formed when two gametes fuse together.

Differential Expression

The process by which different genes are activated in specific cells, leading to distinct traits.

Gonads

The reproductive organs (testes in males and ovaries in females) where gametes are produced.

Primary Sex Characteristics

Organs and features that are directly involved in reproduction.

Secondary Sex Characteristics

Traits that develop at puberty but are not directly involved in reproduction, like breast development or facial hair.

XX/XY sex determination

The genetic system for determining biological sex in humans, with XX being female and XY being male.

Turner Syndrome

A genetic condition resulting from the loss of an X chromosome, leading to female traits but often infertility.

XX Male Syndrome

A condition where an individual with XX chromosomes develops male traits due to a unique Y gene transferred to an X chromosome.

Swyer Syndrome

A condition where an XY individual develops female physical characteristics due to a potential mutation affecting male development.

Interphase

growth, genome duplication etc.

Prophase I

chromatin condenses, nucleus dissolves

Pro-metaphase 1

chromosomes start migration, spindle fibers begin growing

Metaphase 1

spindle fibers connect to chromosomes, aligned along metaphase plate

Anaphase 1

chromosomes are pulled apart to the cell poles

Telophase 1

cleavage forms and the cells begin dividing

Cytokinesis 1

the final steps in cell division, contractile ring pinches cells apart

In S phase in meiosis…

all DNA is duplicated

in prophase 1…

two-non identical copies find each other and interact

homologous match

the other non identical chromosome

tetrad

a group or set of four

when tetrads form the two homologous chromosomes are..

held very close together and are almost tangled up

recombination..

occurs in both parents too

autosomal chromosomes

22/23 chromosomes, non sex chromosomes

children vary in appearance because of

recombination

anaphase 1

tetrads are pulled apart and unbroken chromosome pairs are pulled to poles (sister chromatids are still paired up)

meiosis 2 ends with

4 haploid cells

the 4 haploid cells at the end of meiosis 2…

only have one copy of each chromosome

are all animals dipoid?

no

spermatozoa

very small and motile, short lifespan

ova

large and sessile, long lifespan

turner syndrome

loss of an X chromosome

XX male syndrome

XX karotype

Swyer syndrome

XY karyotype

the red queen hypothesis

species are always chasing the best traits for their environment, but their conditions change before they get there

the red queen hypothesis is…

a concept missed by Darwin

discent with modification

species change over time, give rise to new species, and share a common ancestor

indivisual’s w/ useful traits..

reproduce more (are more abundant)

individual’s w/ harmful traits..

reproduce less (are less abundant)

blood type

example of polyallelic trait with incomplete dominance

antigens

recognizable by our immune system—ignored as “norma”

type A

possesses A antigen

type B

possesses B antigen

type AB

possesses both A and B antigens

type O

possesses neither A nor B

Rh-positive

has Rh antigen

Rh-negative

lacks Rh antigen

antibodies

defensive proteins produced by our immune system, which bind to matching antigens

blood type is a..

polygenic trait

polygenic traits are..

inherently non-mendelian

antibodies two purpose:

1) bind to foreign bodes + immobilize them 2) mark them for destruction

mutations

an origin of variation

mutations can..

be good/neutral/bad

mutations sometimes..

impact phenotype

Mendelians 1 rule: only two alleles are present for each trait” is false because..

only works for diploid life

Mendelians 1 rule: “one allele masks another at the level of the phenotype” is false because

traits can have incomplete dominance or co-dominance

a mutation arises during..

cell reproduction

2 goals of meiosis

1) reduce to haploid 2) recobination

All cells perform mitosis except…

sex cells

somatic cells

Any cells in the body other than reproductive cells

reproductive cells

gametes

paternal gamete

1. sperm

2.pollen

maternal gamete

egg

anisogamous gameates

morphologically different between sexes

ploidy

number of sets of chromosomes

Gametes ploidy

haploid

somatic cells ploidy

diploid

cross over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

genetic cross

breeding 2 individuals to make offspring

monohybrid cross

genetic cross that had parents that defer in one phentotype

p

parental generation

f1…f2…f3…

subsequent filial gen

allele

a variant form of a gene

locus (loci)

location in the genome

Homozygous

An organism that has two identical alleles for a trait

dominant alleles

An allele whose trait always shows up in the organism when the allele is present.

recessive allele

An allele that is masked when a dominant allele is present

Mendels principal 1

everyone only had 2 alleles for each trait, one is dominant and one is recessive

Mendels principal 2

genes become segregated during gamete formation, so each offspring inherits only one copy from parent

Mendels principal 3

each gene is sorted independently-which copy the parent passes on is random for ewach gene

model organisms

organisms that are easy to observe and manipulate

evolution

gradual change to population of related organism across generations

generation

average time it takes for population to replace itself

Codominance

BOTH dominant, get expressed organism patchily

incomeplete dominance

one allele is not completely dominant over another, expressed into third phenotype

polygenic

multiple genes affecting a given trait

Extirpation

local extinction

Extinction

globally gone

migration

leaving population

vestigial trait

Traits that persist despite no longer serving a purpose.

natural selection

the ENVIRONMENT places selective pressure on traits that are less useful to the organism