cell division Flashcards
what happens in prophase I
chromosomes condense
centrioles move to the pole
nuclear membrane breaks down
centrioles start to make spindle fibres
what happens during the bivalent formation
chromosomes cross over
certain genes are transferred
what is synapsis
the process of pairing up homogolous chromosomes
what is a chiasma
the point at which chromosomes cross over
what happens during metaphase I
4 chromatids line up at equator
centromere attaches the chromosome to the spindle
what happens during anaphase I
bivalent seperation (pull chromosomes apart)
centromeres do not divide (break apart chaisma)
what happens during telophase I
2 new nuclear envelopes form
what is a gene locus
position of a gene on a chromosome
what happens during the process of synapsis
the process of pairing up the homologous chromosomes
what is the asexual reproduction in yeast
budding
outline the process of the asexual process in yeast
mitosis
small bud emerges from mother cell
enlarges until it reaches a certain size
separates from the mother cell
why does genetic material need to replicate before the nucleus is divided (2 marks)
genetically identical
correct amount of DNA
what is a homologous pair of chromosomes (3 marks)
maternal and paternal genes
carry same genes
carry same alleles
what is the function of squamous epithelium
acts as a surface
where is squamous epithelium found
alveoli
give 2 examples of where to find meristem tissue
root
shoot
what is the nuclear division that occurs in meristem
mitosis
what are the stages of the cell cycle
interphase
mitotic
cytokinesis
what are the 3 stages in interphase
G1
S
G2
what happens in G1 (2 ways)
cell size doubles
cell synthesis
what happens in the S phase of interphase
DNA replicates
what happens in G1
organelles divide
give 3 reasons why mitosis occurs
growth
cell repair
asexual reproduction
what are the 4 phases of the mitotic phase
prophase
metaphase
anaphase
telophase
what are the 3 things that occur in prophase
chromosomes condense
centrioles move to opposite sides of the cell
nuclear envelope and nucleolus breaks down
what happens in metaphase
chromatids line up on the equator
what happens in anophase
spindle fibres contract
chromatids seperate into 2 different chromosomes and are pulled to opposite poles of the cell
spindle fibres break down
what happens in telophase
chromsomes decondense
nuclear envelope form around each set of chromosome
what are the 2 things that happen in cytokinesis
cell membrane forms cleavage furrow
division of cytoplasm
what enzyme and protein initates the next phase of the cell cycle after a checkpoint
kinase enzymes
phosphorylate proteins
what are the products of meiosis
4 haploid cells
half the number of DNA
what are the
