Cell Division Flashcards
cell continuity
all cells develop from pre existing cells, in order to do this all living cells need to divide
function of cell division on unicellular organisms
asexual reproduction
function of cell division in multicellular organisms
growth and repair of cells
sexual reproduction
what are chromosomes?
thread like structures found in nucleus
how many chromosomes are in each human cell?
23 pairs ie 46 total
composition of chromosomes
DNA and Protein
genes
lengths of DNA that code for the production of a protein
diploid
cells with 2 types of each chromosome
what symbol is given to diploid cells
2n
what are matching chromosomes called?
homologous pairs
haploid
one type of each chromosome ie egg and sperm
what symbol is given to haploid cells
n
what are the 2 phases of the cell cycle
cell division
interphase
what is interphase
the stage of the cell cycle where the cell is not dividing
how much time does interphase take up
roughly 90%
what processes occur during interphase
cell growth
DNA replicates
organelles are made
make up of chromatin
DNA and protein
when is chromatin present
interphase
when are chromosomes present
dividing
differences between chromatin and chromosomes
CHROMOSOMES
tightly packed DNA
condensed thick fibres
cell is dividing
chromosomes are paired
CHROMATIN
unravelled DNA
elongated, thin fibres
cell is not dividing
chromatin not paired
mitosis
form of nuclear division in which 1 nucleus divides to for 2 daughter nuclei each with the same no of chromosomes and identical genes
meiosis
form of nuclear division in which 1 nucleus divides to give 4 nuclei each with half the number of chromosomes as the parent.
role of mitosis
growth and repair
asexual reproduction
what are the 4 stages of mitosis
prophase
metaphase
anaphase
telophase
(pour me another tea)
chromatid pairs
all chromosomes replicate themselves before cell division. the 2 precise identical chromosomes are called a chromatid pair
centromere
structure on chromosomes that holds a pair of chromatids together
centriole
organelle in cytoplasm that produces spindle fibres
spindle fibres
filaments that attach to chromosomes during mitosis to move chromosomes and pull chromatid pairs apart
describe prophase
-chromosomes contract and become visible
-spindle fibres are forming
-nuclear membrane is breaking down
describe metaphase
-chromosomes are line dup along the equator
-spindle fibres are attached to chromosomes at centromere
-centrioles are at opposite poles of the cell
describe anaphase
-spindle fibres contract
-single strand from each chromosome pair is pulled to either pole of the cell
which is the shortest phase
anaphase
describe telophase
nuclear membrane has reformed
spindle fibres are broken down
chromosomes have elongated again
2 nuclei are formed that are genetically identical
explain cytokinesis in animal cells
cell membrane drawn inwards at equator forming a cleavage furrow which eventually splits cell in 2
when does cytokinesis occur?
straight after telophase
explain cytokinesis in plant cells
cell plate forms along the equator
cell plate divides the cell and middle lamella fills the region between the 2 new cells
what are vessicles made from
cellulose
what makes the cell plate
vesicles
function of meiosis
sexual reproduction
variation in population
list the differences between meiosis and mitosis
mitosis
2 daughter cells
same no of chromosomes in parent and daughter cells
daughter cells are genetically identical to parent
meiosis
4 daughter cells
half no of chromosomes in daughter cells
daughter cells are genetically different to each other
cancer
a group of disorders in which a certain cells lose the ability to control the rate of mitosis
how do tumours form
cells that lose control of their mitosis rate form a mass of cells ie a tumour
benign tumour
non life threatening tumours. it is formed but does not invade or interfere with the functioning of other cells or tissues
malignant tumours
this mass of cells may be harmful to other cells and tissues in the body preventing the efficient functioning of other cells
metastasis
the movement of tumours through the blood system to another part of the body, further invading the body
what is a carcinogen
a cancer causing agent
give examples of carcinogens
UV rays, cigarrettes, vapes, tobaco
treatments of cancer
surgery, chemo, radiation therapy
why cant red blood cells undergo mitosis?
they do not have a nucleus and no mitochondria
what type of division can haploid cells go through?
mitosis only
what type of division can diploid cells go through?
both
