b2.3- cell specialisation Flashcards
impact of gradients on gene expression within an early-stage embryo
- cells are unspecialised at first
- as embryo grows, the cells develop along different pathways and become specialised for different functions
- becomes more efficient
definition of stem cells
- cells capable to carry out cell division
- not differentiated into specialised cell yet
stems cells function [2]
- differentiate along different pathways
- retains the capacity to divide
totipotent
can become any cell type or a single organism
eg. zygote cells
pluripotent
any type but not a single organism
eg. embryonic stem cells
multipotent
similar group of cells
eg. bone marrow -> various blood cells
unipotent
only one cell type
eg. liver (can regenerate)
nullipotent
cannot divide
eg. red blood cells
location of function of hair follicles
to grow hair
location and function of bone marrow
center of most bones and in the end of spongy bones
creates blood cells and platelets for your blood
why growing cells tend to divide and remain small
maintain high SA:vol ratio
- fast exchange of nutrients, small distance
- reaction would generate heat
when size of a cube increases- SA:vol ratio
decreases drastically
eg. 1x1x1 cube
SA= 6 cm2
vol=1 cm3
ratio= 6:1
2x2x2 cube
SA= 24 cm2
vol= 8 cm3
ratio= 3:1
autotroph
an organism that can produce its own food
heterotroph
an organism that eats other plants or animals for energy and nutrients
another term for red blood cell
erythrocytes
adaptations to increase SA:vol ratio [5]
- flattening
eg. erythrocytes
- biconcave shape - microvilli
eg. proximal convoluted tubule (first bit of the nephron tubule)
- distance (folds) + speed (lots of turns so slower) : more time to get all the glucose back - invaginations/ folds
eg. cristae in mitochondria - compartmentalisation
- maintain concentration gradient
function of ATI
diffusion of oxygen and carbon dioxide (gas exchange)- passive process
adaptations of ATI
- very thin
- distance over where oxygen and carbon dioxide must diffuse is very small
function of ATII
- makes and store phospholipid
adaptations of ATII
- rough er- make phospholipid
- vesicle- release phospoholipid
functions of striated muscle cells
movement
- doesnt need to be fast/ in unison
adaptations of striated muscle cells
- unbranched
function of cardiac muscle cells
to pump blood around body in using electrical signal in a particular rhythm
adaptation of cardiac muscle cells [3]
- branched
- so electrical impulses can spread very fast - joined end to end
- myogenic
adaptation of an egg [2]
- zoda pellucida- very thick
- makes sure only one sperm can enter - thick cytoplasm
- contain a lot of nutrients to make embryo
function of sperm
transfer a haploid nucleus form the testis of a male to the cytoplasm of an egg cell in the oviduct of a female
adaptation of sperm [4]
- acrosome (enzyme)- digest zona pellucida
- change protein on the zona pellucida so other sperm’s acrosomes wont work (enzymes are specific)
- long tail- adapted to swim fast to the egg
- many mitochondria
- provide ATP to ensure that the sperm can get to the egg
rate of diffusion is proportional to
surface area
rate of metabolism is proportional to
volume
why small cells are more efficient than big cells
- higher SA:vol ratio
- diffusion distance short, less time needed
special feature of a giant alga that is an exception to the cell theory
lacks subdivision into separate cells
