bio fondations final

a cell division process by which prokaryotic cells replicate

binary fission

4 key processes of binary fission:

1. chromosome is duplicated so that the cell has 2 complete copies of its DNA sequence

2. the 2 copies of the chromosome are physically separated to to the opposite ends of the cell

3. the cell membrane pinches in the middle to separate the 2 cells

4. the pinched membrane combines with itself so that the 2 separate cells are made

chromosome is duplicated so that the cell has 2 complete copies of its DNA sequence

DNA replication

the 2 copies of the chromosome are physically separated to to the opposite ends of the cell

chromosome segregation

the cell membrane pinches in the middle to separate the 2 cells

cytokinesis

the pinched membrane combines with itself so that the 2 separate cells are made

cell separation

the cell cycle replication process in eukaryotes

mitosis

periods between rounds of mitosis

interphase

G₁ phase of interphase

• phase of growth and performing physiological jobs

• where most of a cell life is spent

cells become larger and make more organelle and proteins

growth

each cell in an organism performs their specialized life functions

performing physiological jobs

Synthesis (S) phase

where a cell replicates- the cell’s chromosomes are copie

eukaryotic cells are more…

complex and greater in number compared to prokaryotes

prokaryotic chromosomes

• only 1 circular chromosome

• chromosome not kept in a nucleus

where are prokaryotic chromosomes

floating in region of the cytoplasm called the nucleoid

in order to fit inside of the cell prokaryotic chromosomes…

chromosome twists (supercoils) itself to fit in the cell

eukaryotic chromosomes

typically have multiple linear chromosomes

proteins that wrap around the DNA of eukaryotic chromosomes

histones

combination of DNA and DNA wrapped around histones

nucleosome

nucleosomes are twisted together into a chromosome by

supercoiling

most of the time chromosomes are found as loosely pinched ball of fibers called

chromatin

fibers are formed by…

supercoiling of nucleosomes

during interphase to fill the entire nucleus chromatin…

typically spreads out

when mitosis happens the chromosomes

condense into densely packed structures

every species has a different number of…

chromosomes

once the chromosomes have been copied during the S phase each homologous chromosome…

has 2 complete copies of each other

every cell in an individual has…

one complete set from each parent

the chromosomes of each pair

homologous chromosomes

identical copies of each homologous chromosome are

sister chromatids

region of chromosome where the sister chromatids attach together

centromere

what is used to stick the 2 sister chromatids together at the centromere

cohesions

Second Gap (G₂) phase

• cell prepares for mitosis

• checks and repairs copying erros

• cell starts producing the enzymes and other proteins needed for mitosis

process in which the copy made of the chromosome during S phase is checked for copying errors and those errors are repaired

DNA proofreading

chromatin condenses into dense distinct mitotic chromosomes during

prophase

in prophase the proteins of the cytoskeleton reorganize to form a structure called

mitotic spindle

in prophase the mitotic spindle will eventually…

separate the chromosomes during chromosome segregation

the nuclear envelope breaks apart and releases the chromosomes into the cytoplasm

prometaphase

in prometaphase the mitotic spindle attaches to the chromosome at a…

protein-based structure called the kinetochore

the mitotic spindle makes small adjustments that line up each homologous chromosome at the middle of the cell in

metaphase

digestive enzymes destroy the cohesions holding the sister chromatids together and the mitotic spindle pulls the chromatids to the opposite ends of the cell in

anaphase

the mitotic spindle pulls the chromatids to the opposite ends of the cell

chromosome segregation

nuclear envelope re-forms around the segregated chromosomes and mitotic chromosomes decondense into chromatin

telophase

in animal and plant cells mitosis also has several distinct phases called

cytokinesis

• mitotic spindle breaks down

• a ring of plasma attached to the plasma membrane and pinches the membrane together

• at the end of the process the plasma membrane combines with itself to produce 2 separate cells

cytokinesis in animal cells

process where the plasma membrane combines with itself to produce 2 separate cells

cell separation

• mitotic spindle remains

• spindle assembles vesicles made by the golgi at the middle of the cell

• vesicles come together to form a cell plate

• cell plate creates 2 separate cells

• after cell separation mitotic spindles break down

cytokinesis in plants

vesicles contain the materials needed to build the

plant cell wall

asexual reproduction reproduces genetically

identical offspring

bacteria and other unicellular prokaryotes reproduce by

binary fission

most unicellular prokaryotes reproduce by

some variation of mitosis

sexual reproduction reproduces genetically

different offspring from their parents

cells that perform the body’s normal functions outside of reproduction

somatic cells

somatic cells typically have

2 complete sets of chromosomes one from each parent

cells that have 2 complete sets of chromosomes

diploid

somatic cells perform ___ to ___ cell rather than reproduce the organism

mitosis, replicate/regenerate

specialized cells produced by germ cells for reproduction

gametes

gametes have ___ complete set of chromsomes

one

cells that have one complete set of chromosomes

haploid

in some organisms like humans gametes differ in size and shape

anisogamy

larger gamete

female

smaller gamete

male

in some organisms gametes are the same shape and size

isogamy

in sexual reproduction each gamete is a

haploid cell with one set of chromosomes

one cell of each mating type will fuse together

fertilization

fertilization produces a

single diploid cell called a zygote

the organism reproduces its somatic cells from

the zygote by mitosis

process of producing gametes

meiosis

meiosis is a…

modified version of mitosis

in meiosis the body starts with

one diploid germ cell

that one germ cell goes though

2 consecutive rounds of cell division, meiosis 1 and meiosis 2

at the end of meiosis that one germ cell produces

4 haploid gametes

the main difference between meiosis and mitosis is

how the chromosomes behave during that process

in mitosis the chromosomes are lined up and separated in a way that makes

cells it produces genetically identical

in meiosis the chromosomes are lined up and separated in a way

that makes the cell it produces genetically unique

in prophase I

bivalent chromosomes have 2 homologous chromosomes physically connected together

physical connection of chromosomes

synapsis

the chromosomes become “glued” together by a set of proteins that form the

synaptonemul complex

during synapsis the homologous chromosomes are able to swap entire sections of their DNA with each other

chiasma

crossing-over creates hybrid (recombinant) chromosomes that have

some DNA from both parents

crossing-over creates

new unique combination of genes on each chromosome