cell division Flashcards
what is the purpose of mitosis
cell growth (increase in cell no.)
to repair (replacing damaged cells)
asexual reproduction
what happens in G1
cell growth
organelles are produced and replicated
what happens in the S phase
DNA replication
what happens in G2
cell growth
energy stores
what happens during mitosis
nuclear division
what happens during cytokinesis
cell division
what happens in G0
cells are unable to divide actively
how is the cell cycle controlled
genetic checks to make sure DNA is mutation free
what does the spindle assembly checkpoint check for
chromosomes attachment to spindle
what does the G1 checkpoint check for
cell size
nutrients
growth factors
DNA damage
what does the G2 checkpoint check for
cell size
DNA replication
DNA damage
what happens during prophase
DNA coils to form chromosmes
nuclear membrane breaks down
centrioles move to opposite poles of cell creating spindle fibres
what happens during metaphase
chromosomes attach to spindle fibres at the centromere
spindle fibres move chromosomes so they align at the equator of the cell
what happens during anaphase
spindle fibres contract
centromere splits
chromatids separate
chromatids are pulled to opposite poles of the cell
what happens during telophase
DNA uncoils to form chromatin
nuclear membrane reassembles
spindle fibres start to break down
give the differences between animal and plant cells during mitosis
plant
- centrioles only appear during mitosis
- cell wall regrows
- cell wall grows from inside to out to divide cell
animal
- centrioles always present
- no cell wall
- cell surface membrane pulled into divide cell
how do you calculate mitotic index
no of cells in mitosis/total no of cells
what happens during prophase 1
DNA coils to form chromosomes
nuclear membrane breaks down
centrioles move to poles of cell producing spindle fibres
homologous chromosomes pair up and form bivalent pairs
what happens during metaphase 1
bivalents line up along equator
centromere attaches to spindle fibres
independent segregation takes place
what happens during anaphase 1
spindle fibres contract
homologous chromosomes separate and are pulled to opposite poles of the cell
what happens during telophase 1
chromosomes uncoil
nuclear membrane reforms
nucleus reappears
what happens during prophase 2
DNA coils up to form chromosomes
nuclear membrane breaks down
centrioles move to opposite poles of cell producing spindle fibres at 90 degrees to prev division
what happens during metaphase 2
chromosomes align at the equator
centromere attaches to spindle fibres
what happens during anaphase 2
spindle fibres contract
centromere splits, chromatids separate
chromatids are pulled to opposite poles
what happens during telophase 2
DNA uncoils, nuclear membrane regrows
nucleus reforms
what is independent segregation
refers to the random separation of homologous chromosomes during meiosis I. This process contributes to genetic variation by producing different combinations of alleles in the resulting daughter cells
how do you calculate the number of possible gametes
2^n - where n is the chromosome number
what is crossing over
during metaphase 1, non sister chromatids wrap around each other, chiasma forms, DNA is exchanged between chromatids
what are the adaptations of an erythrocyte
biconcave disc - larger SA:V
haemoglobin - binds to 02 easily
no nucleus
flexible membrane - can squeeze through narrow capillaries
what are the adaptations of a neutrophil
granular cytoplasm - contains many lysosomes (digestive enzymes)
multilobulated nucleus - can fit through capillary gaps and reach infection
what are the adaptations of a sperm cell
many mitochondria
acrosome
haploid nucleus
flagellum
what are the adaptations of guard cells
cell wall thicker on inside so volume change doesnt change shape of cell symmetrically
what are the adaptations of a palisade cell
many chloroplasts
tall and thin - can be densely packed together
vacuole - pushes chloroplasts to outer part of cell
thinner cell wall
what are the adaptations of a root hair cell
long extension - increases SA:V
many mitochondria
thinner cell walls
what are the adaptations of a xylem
lignin - provides structural support
what are the adaptations of phloem
sieve plates - allow easy flow of nutrients
give examples of epithelial tissue
squamous (blood vessels + alveoli)
columnar (digestive tract)
ciliated (respiratory tract)
what is the purpose of epithelial tissue
covers body surfaces (acts as a barrier) and facilitates diffusion
what is the purpose of connective tissue
provides structural support to other tissues and acts as a transport medium
give examples of connective tissue
cartilage
what are the 3 types of muscle tissue
skeletal
smooth
cardiac
what is the purpose of nervous tissue
transmits electrical signals
what is epidermal tissue
outer protective layer of plant covered by waxy cuticle
what is the purpose of ground tissue
storage of food and water, provides structural support
give an example of ground tissue
mesophyll
give examples of vascular tissue
xylem and phloem
what are totipotent stem cells
can divide and produce any type of body cell
(only occur in very early mammalian embryos)
what are pluripotent stem cells
can differentiate to wide range of cell types in unlimited numbers and can be used to treat human disorders
what are multipotent stem cells
can divide to form a limited number of different cell types
what are unipotent stem cells
can only divide to one type of cell eg cardiomyocytes
what are induced pluripotent stem cells
produced from adult somatic cells using appropriate protein transcription factors
what are transcription factors
chemicals that bind to DNA and stimulate/inhibit transcription/RNA polymerase
give the potential medical uses of stem cells for damaged tissues
macular degeneration
cardiovascular disease
diabetes type1
give the potential medical uses of stem cells for neurological conditions
parkinson’s
alzheimer’s
give the potential research uses of stem cells for developmental biology
how cells specialise
embryo development
what are the sources of stem cells and what potency do they produce
bone marrow (multi)
umbilical cord (multi)
aborted/ still born foetuses (pluri)
spare embryos from IVF (pluri)
meristem
what are the ethical concerns with stem cells
embryos - right to life and informed consent
