Cell Division Flashcards
what are the 2 points to cell theory
- all organisms are made out of cells
- new cells can only be made when existing cells divide
what is the importance of mitosis
used for growth, to replace old or damaged tissue or for asexual reproduction
describe the daughter cells produced by mitosis
2 genetically identical diploid daughter cells (contains 2 sets of chromosomes)
what type of cells does mitosis happen in
somatic cells (cells that don’t form gametes)
what are somatic cells
cells that dont form gametes
where does meiosis occur
in cells in reproductive organs, i.e gametes
describe the daughter cells produced by mieosis
2 genetically different haploid daughter cells (contains 1 sets of chromosomes)
what is the importance of mieosis
produces gametes for sexual reproduction
True or false prokaryotes don’t divide by meiosis or mitosis. how do they divide
true, divide by binary fission
defintiion of haploid cell
cell with a single set of chromosomes
defintiion of diploid cell
cell with 2 sets of chromosomes
cell cycle definition
the highly ordered sequence of events (1) that result in nucleus division (2) and formation of 2 genetically identical daughter cells (3)
what is m phase
mitosis phase: cell growth stops, and nuclear division occurs: prophase, metaphase etc.
what is G0 phase
growth 0 phase: when cell leaves the cell cycle temporalily or permanently
what 3 things happen in G0 phase
apoptosis, differentiation or senescence
what 3 things happen during growth 1 (G1) phase
cells increase in size
organelles duplicate
biosyntheiss (any synthesis reactions in cell)
what gene helps to control growth in G1 phase
p53 tumour supressor gene
what happens at synthesis phase in interphase
DNA replicates; resulting in chromosomes
qhat happens at G2 phase
growth 2 phase: cell contineus to grow; energy stores increase
apoptosis defnitiion
programmed cell death; when cell is damaged
senescence definitipn
when a cell ages and permanteley stops dividing but doesn’t die; irreversibel GROWTH ARREST
differentiation role in G0 phase
a cell that is specialised and no longer able to divide e.g red blood cells
what is the importance of cell-cycle checkpoints
prevents uncontrolled division
repairs any errors in DNA replication
what is the G1 checkpont called
restriction point
what is the fucntion of G1 checkpoint (4)
checks for:
- cell size
- nutrients
- growth factors
- DNA dmamage
what is the fucntion of G2 checkpoint (4)
checks:
- cell size
- DNA replication
- DNA damage
function of spindle assembly checkpoint/ metaphase checkpoint (2)
check is chromosomes are attached to spindles (1) and are aligned(2)
what is the order of phases in mitosis
prophase,l metaphase, anaphase, telophase, cytokinesis
prophase function
- chromatin in nucleas condenses & nclear envelope disintigrates
- spindle threads of tubulin forms from centriole (in animals)
metaphase function
pairs of chromatid attach to the spindle fibres by their centromere at the equator region
anaphase function
the centromere of each pair of chromatids splits
contraction of spindle fibres pulls chromatids apart
telophase function (2)
separated chromosomes reach the poles and DEcondense (1)
nuclear membrane reforms resulting in 2 genetically identical nuclei (2)
cytokinesis function (in animals)
plasma membrane folds inwards and pinches at teh cytoplasm
cytokinesis function (in plants)
an endplate forms where the equator of the spindle was. new plasma membrane and cellulose cell wall are laid on either side of plate
mitosis defintiion
Mitosis is the process of replicating and diving the genome
cytokinesis definition
cytokinesis is the physical division of
the cell
limitation of lock and key model
it doesn’t explain why the activation energy gets lower
what is the technical term for RBC
erythrocytes
RBC function and technical name
erythrocytes: carries O2 from lungs to respiring cells
what organelles does RBC nt have
golgi apparatus, nucleas, little cytoplasm
name adaptations which help for RBC’s fucntion
small & bioconcave = small SA:V ratio
few organelles = increase in haemoglobin inside
flexible cytoskeleton - moveemnt through capillaries
neutrophils defnition
type of phagocytic WBC that injests invading pathogens , makes up 50% of WBC
name structure adaptations of neitrophils
contaisn many lysossomes -= digestion
contains multilobid nuclear & has flexible cell membrane - pass between cells & tissues
what is the name for the cell which ‘is a male gamete that delivers genetic information to the ovum’
spermatozoa
structure of spermatozoa
flagella = movemebt
many mitochondira = energy to swim
ACROSOSME on sperm head contains digestive enzymes = breaks down protective layers of ovum
cambium defintiion
source of undifferentiated cells in the vascular bndle of plants
squamous epithelium definition
layer of flattened cells (1) present in areas which need rapid diffusion
squamous epithelim structure
single layer of cells(1)
relatively unspecialised (2)
basmeent memebrane underneath epithelium layer(3)
what is basement layer
thin membrane of protein fibres & polysaccarides separating epithelium from the other tissue
root hair cells location
surfaces of roots near the growing tops
root hair cells function
maximises uptake of water and miberals from the soil
root hair cells adaptation
root hairs (long extensions attached to cell membrane) increases surface area of cell
palidase mesophyll cells fucntion
contaisn increased amoutn of chloroplasts for large absorption of light for photosyntheiss
palisade mesophyll cells adaptations (2)
thin cell walls = more CO2 absorption
rectangular shapes = tightly-packed tissues
guard cells function
pairs of guard cells form small openings: stomata; controls CO2 into plant and to some extent water loss from plant
guard cells adaptations
when guard cells lose water = less swollen = changes shape = stroma is closed to prevent further water loss
meristem definition
an area of undifferentiated plant cels that can divide by mitosus and differentiate into a range of plant cell types
connective tissue definition (2)
sperates living tissues & can withstand forces such as weight (1)made of non-living extra cellular matrix (2)
what is non-livinf extracellular matrix in connectibve tissue made out of?
proteins: collagen and elastin
polysaccarides: hyaluronic acid
name 2 types of connective tiddue
cartilage and muscle
definition of cartilage
firm & flexible connective tissue, composed of chondrocyte cells, ti prevent bone runbbing which can cause damage
what are fish bones made out of
cartilage
what are the 3 types o muscles tissues
skeletal muscle fibres, cardiac muscle, smooth muscle
skeletcal muscle function
attached to bone & tendons; contains myofibrils which contain contractile proteins
cardiac muscle functinn
makes up walls of heart to beat & pump blood
smooth muscle function
walls of intenstines & blood vessels
name 3 types of cartilage
elatin, fibrous and hyaline
where is elastin found
in the trachea & external earlobes
fibrous found
ends of bones in joints
hyaline found
young skeelton & joins ribs to the sternem
what 2 cells are responsbele formainatining the extracellular matrix, which of these are immature & make the matrix and which is mature and repairs the matrix
chondroblasts: immature & makes the matrix chondrocytes: mature and repair teh matrix
puropose of waxy cuticle
redcues water loss from evaproration & trasnipiration
gurad cells fucnton
allows CO2 in & out of leaves and consequently also water and O2
epidermis (of a plant) definition
single layer of closely packed cells with a waxy cuticle, often has a stomaat and guard cells
xylem tissue definition (3)
type fo vascular tissue for transmitting water and minerals in transcripition(1), 1 way system (2) made of elongated deas cells with no end wall (3)
which is 1 way which is 2 way system between xylem and phloem
xylem: 1 way transcription
phloem: 2 way translocation
structure of xylem tissue(3)
elongated dead cells strengthened by lignin (1) with no nucleas and little cytoplasm (2) and no end wall (3)
phloem definition
type pf vascular tissue for transporting sucrose in translocation (2way)
phloem structure
sieve tubes cells perforated ends by sieve plates
vascular systems defintiion
network of tissues e.g xylem & phloem transporting water and minerals
ehy are flowers seen as an organ system?
contians differen organs e,g sepals, petals, stomens & ovaries
stem cell defintion
renewing source of undifferentiated cells
key features of stem cells
- able to express all genes
- can divide by mitosis to produce more stem cells
cell potency defition
ability of a stem cell to differenitate into different cell types
totipotent defintion
any body cell including placenta and umbillical chord; can grow into ful organism e.g zygote & early embryo
pluripotent definition
any body cell except extra-embryonic cells; can’t grow into a full organism
multipotent definition
form 1 type of cell but not all e.g adult stem cells
unipotent definition
unspecialised cells; continuously dividing into new cells e/g skin stem cells
what potency is meristem an vascular cambium?
multipotent
where is meristem present
plants: roots & shoots
name 2 types of meristem found in plants
cambium & meristem
where is cambium present
sandwhiched between xylem and phloem
From the centre outwards, what is the order of phloem, xylem and cambium
xylem, cambium, phloem
what 2 things happen when cambium turn to xylem & why?
- lignin deposited in cell wall = to waterproof
- ends of cells break down = continuous column
what 2 things happen when cambium turn to phloem & why?
- cambium lose most of their organelles then sieve plates develop between them
- companion cells retain organelles & provide ATP for sieve tubes
