b2 Flashcards
why are new cells needed?
for growth and repair
what is the cell cycle?
where cells grow and divide repeatedly
why do cells in your body divide?
produce more cells so your body can grow and replace damaged cells.
what’s it called when cells grow and divide repeatedly?
The cell cycle
what sub-categories is interphase divided into?
G1
S (synthesis)
G2
what is the first stage of cell cycle?
Interphase
the cell grows and replicates its DNA in preparation for division
what is G1 in the cell cycle?
The cell grows and carries out its normal metabolic functions, and prepares for DNA synthesis
GAP PHASE 1
how is DNA replicated?
.DNA unzips
.complimentary base-pairing
what is G2 in the cell cycle?
The cell continues to grow and prepare for cell division
GAP PHASE 2
what is S phase in the cell cycle?
The cell synthesizes a copy of its DNA, which is replicated during this phase
SYNTHESIS
what is Mitosis?
cell division which produces two identical diploid daughter cells
steps of mitosis
starting with the cell having 2 copies of its DNA?
.DNA spread out
.DNA forms x chromosomes
.Chromosomes LINE up in middle
.x is pulled apart to OPPOSITE ends
.membrane forms around each side - surrounding chromosomes
.CYTOKINISIS - cytoplasm divides
.
.no have 2 genetically identically diploid daughter cells
What is the second stage of the cell cycle?
Mitosis
cell divides into 2
what is cytokinesis?
stage during which the cell physically divides into two daughter cells
what is the third stage of the cell cycle?
CYTOKINISIS
what is differentiation?
process by which a cell changes to become specialised to its job
why is having specialised cells good?
allows organisms to work more efficiently
what is the palisade leaf cells?
SPECIALISED CELL
.do most of photosynthesis
.packed with chloroplasts
.TALL shape = large SA exposed down side for absorbing CO2
.THIN shape means can fit loads on top of a leaf, nearer to the light
what is the sperm cell?
SPECIALISED CELL
.get male DNA to female DNA during reproduction
.LONG tails and STREAMLINED heads help them swim
.contain a lot of mitochondria provide them with energy
.enzymes in their head to digest through egg cell membrane
What are stem cells?
undifferentiated cell of an organism which is capable of dividing by mitosis
those new cells then can differentiate
what are Embryonic stem cells?
found in early embryos and are completely undifferentiated.
This means that they can be used to turn into any type of cell.
what are adult stem cells, where are they found?
Stem cells can be found in the bone marrow, teeth and other areas.
These cells cannot differentiate into any type of cell
what are adult stem cells used for in animals?
replace damaged cells
-make new skin
-more blood cells
what are meristems?
What is the role of a meristem?
type of tissue found in plants
produce unspecialised cells that have the potential to become any type of specialised cell.
what does meristem contain?
plant stem cells
where is meristem tissue found?
areas of plant that are growing
ROOTS AND SHOOTS
what is diffusion?
NET movement of particles from an area of HIGH concentration to an area of LOW concentration
how can substances move in and out of cells?
diffusion
active transport
osmosis
what can diffuse through the cell membrane?
SMALL molecules
glucose, amino acids, water and oxygen
-starch and proteins CANNOT FIT
what is active transport?
the movement of substances AGAINST their concentration gradient
using the ATP (energy) released during respiration