Chapter 16: mitosis and meiosis

cell cycle

life cycle of a cell

somatic cells

body cells, go through mitosis

asexual reproduction

no combination of cellular material occurs

• all new cells contain the same genetic material as the original cell (clone of og cell)

why cells reproduce

• growth (adding new cells)

• maintenance (replacement of cells)

• repair (regeneration of damaged tissue)

parent cell

original cell that divides to produce two new daughter cells

daughter cell

any one of the cells produced from the division of the parent cell

fragmentation

a type of cloning where a broken-off section of an organism is able to grow into a new genetically similar organism

• starfish

DNA

contains genetic information of a cell

• governs processes of heredity in the cells of an organism

chromosome

length of DNA, associated with proteins

centromere

the point where 2 sister chromatids are joined

• where the spindle fibers attach during mitosis

chromatin

mass of long intertwined strands of DNA

eukaryotic cell

makeup plants fungi and animals

• have large membrane-bound nucleus

homologous chromosomes

similar looking chromosomes with the same banding pattern

autosomes

pairs of homologous chromosomes numbered 1-22

mitosis

production of the same cell

• haploid (n) → haploid

• Diploid (2n) → diploid

sex chromosomes

carries the genes involved in determining the genetic sex of an individual

• AFAB has 2 X chromosomes

• AMAB has X and Y chromosomes

genes

areas of DNA that contain specific information at the same location

• homologous pairs contain the same genes

alleles

different forms of a gene

• homologous pairs carry different alleles

diploid

a cell that contains pairs of homologous chromosomes

• 2n =46

haploid

cell that contains unpaired chromosomes

• gametes

• n=23

gametes

reproductive cells

• sperm and egg

polyploid

has more then 2 homologous chromosomes

• plants

karyotype

the particular set of chromosomes and individual possesses

interphase

cell carries out regular metabolic functions and prepares for cell division

• G1→Sphase→G2

G1 phase

rapid cell growth and metabolic activity

S phase

DNA replicates, making sister chromatids joined at centromere

G2 phase

cell duplicates organelles, and prepares for division

sister chromatids

two chromosomes that are exactly the same connected by the centromere

• happens in S phase

prophase

• chromatin condenses into chromosomes

• nuclear membrane/envelope breaks down

• centrioles move to opposite poles

metaphase

• spindle fibres guide chromosomes toward the middle of the cell

anaphase

• centromere splits apart and sister chromatids separate

• chromatids are pulled to opposite polls

• 1 complete diploid set of chromosomes are formed

telophase

• Chromatid begin to unwind

• nuclear membrane form around each new set pf chromosomes

cytokinesis

division of cytoplasm to complete the creation of new daughter cells

• indentation forms on daughter cells equator and cells are pinched in two

• cytoplasm and organelles and equally divided between the two cells

sexual reproductoin

production of gametes by meiosis followed by fertilisation between genetically distinct parental gametes to produce genetically distinct offspring

meiosis

the process that produces haploid cells in ovaries and testes

• 4 cells with 23 chromosomes each

prophase 1

• chromatin condenses into chromosomes

• nuclear membrane/envelope breaks down

• centrioles move to opposite poles

• chromosomes synapsis and cross over

synapsis

aligning of homologous pairs

tetrad

pair of homologous chromosomes

crossing over

the exchange of genetic material of homologous pairs

Metaphase 1

• chromosomes line up next to their homologous pairs in the middle of the cell

anaphase 1

• homologous pairs are separated and pulled to opposite polls

• 23 sister chromatids are on opposite sides of the cell

telophase 1

• Chromatids begin to unwind

• nuclear membrane forms around each new set of chromosomes

• each new cell is haploid containing 1 set of sister chromosomes

meiosis

production of genetically different haploid cells

• 2n → n

fertilisation

the combination of two haploid cells to make a diploid cell

• 2 cells → 1 cell

gametophyte

the haploid stage in the life cycle of a plant where it produces gametes through mitosis.

sporophyll

A modified leaf that bears sporangia and is responsible for producing and dispersing spores in ferns and other seedless plants.

meiosis 2

same as mitosis but with 23 chromosomes

• makes 4 haploid cells

gametogenesis

the formation of ova and sperm through meiosis

spermatogenesis

process of sperm production

• 4 sperm cells produced

oogenesis

process of egg production

• only 1 egg is produced, other 3 polar bodies sacrifice their cytoplasm to produce 1 large egg

nondisjunction

when chromosomes don’t separate during anaphase

• 1 daughter cell is produced during separation that will lack information and 1 cell will have too much

trisomy

one too many chromosomes (pair becomes a triplet)

monosomy

one too few chromosomes (pair becomes a singlet)

prokaryotes

have a single circular chromosome and no nucleus

binary fission

equal division of cytoplasm a nucleus of an organism resulting in two new organisms

budding

nucleus of organisms cells divide equally but cytoplasm does not

• new cells formed can live as individuals or colonies

regeneration

the development of an entirely new organism from part of the original organism

• restoration of lost body parts

parthenogenesis

asexual reproduction in which an unfertilized egg develops into an adult

cell death

cells in the body divide a finite number of times before they cannot anymore

• spermatocytes and cancer cells have no life span

cancer

rapid uncontrolled division of cells

metastasis

spreading of cancer cells through the body caused by the fact that cancerous cells have lost the attraction each other to

alternation of generation

when an organism can exist as haploid or diploid

• spores (n) are produced by the sporophyte generation (2n)