Summary A level Biology (OCR A) Revision notes- Module 2- Cell structure

CELL
STRUCTURE-




Eukaryotic cells
Organelles
The cytoskeleton
and protein
production
Prokaryotes

, Task Notes Revision Flashcards


eukaryotic cells and organelles

prokaryotes vs eukaryotes
"




microscopy
water

carbohydrates
lipids
proteins
Inorganic 10ns

Biochemical tests
-




separating molecules

nucleotides

DNA

protiensyntnesls
enzymes
factors affecting enzymes
enzyme Inhibition
Cell membranes
DIFFUSION
Active transport
endolexocytosls
OSMOSIS
.




MITOSIS
MEIOSIS

Stem cells and differentiation
.




tissues organs and systems

,Organisms
eukaryotic cells
are either prokaryotic or eukaryotic Single .
celled organisms are made of prokaryotic cells ,
multicellular

organisms are made from eukaryotic cells Eukaryotic cells
.
are complex and Include all animal and plant cells .




Whereas , prokaryotic cells are simpler and smaller e. g. bacteria .




When asked to identify
ANIMAL CELL RER Structures ,
.




Its very important
to be extremely specific e.g .
.




' '

plasma membrane not
plasma membrane just membrane .




golgi
nucleolus

nuclear
f -
g apparatus


envelope plant cells have the same
Organelles but with a few
mitochondrion
extras :
SER °
a cell wall with Plas modesMata
'
which are used as
'
channels
vesicle
for exchanging substances
with adjacent cells .




Cytoplasm
large permanent
°
a ,
vacuole

which is a compartment that


PLANT CELL
contains cell sap
°
Chloroplasts .
A
envelope
.




nuclear


Chloroplast nucleolus



-
RER




mitochondria




ribosome


large permanent vacuole




I

\ cellulose cell wall

, plasma membrane
found the surface of animal cells and just inside
'




The membrane on

the cell wall in plant cells and prokaryotic cells .
It is made of mainly
lipids ( phospholipid bilayer ) and protein It regulates
.
the movement of

substances into and out of a cell .
It also has receptor molecules on it ,
which allow it to respond to chemical changes like hormones .




Cellwall
#


cytoplasm

A rigid structure that surrounds plant cells Its made
.

mainly of
the carbohydrate cellulose to support and provide strength to plant
cells . / More specifically prevents cells
bursting when they become turgid !




nvcbeog
A large organelle surrounded by a double membrane ( nuclear envelope )
which has It contains chromatin which Is made from
many pores .




DNA and proteins .




It controls the cells activity by controlling the transcription of DNA

The nuclear envelope allows substances to leave and enter .




The nucleus also has a structure called the nucleolus .
It has no membrane ,

contains RNA and makes ribosomes
o -
o
o
.
.
.
.

. "




O




EXAMPLE OF A SUBSTANCE THAT LEAVES → ribosomes or MRNA

EXAMPLE OF A SUBSTANCE THAT ENTERS → steroid hormones



- '




nuclear
.
.
-
.
. .




i :
.



°
envelope
.




.
-
o o:
.
-
" -
.
.

' O

nucleolus
,
.
-


- o .




receptors
pores
..
nuclear
envelope

,lysosome
A round organelle surrounded by a membrane , with no clear internal

structure .
Contains digestive enzymes which are kept separate from the

cytoplasm by the surrounding membrane
,
and can be used to digest invading
cells or to break down worn out components of the cells or to break

down worn out comp on merits of the cell .

They are involved in cellular

apoptosis Phagocytic .
cells would contain many of these to digest invading
cells .

They a 're made by the Golgi as they are a type of vesicle .




ribosomes
A very small organelle which either floats free in the cytoplasm or

IS attached to the rough endoplasmic reticulum . Its made up of proteins
and RNA .
Not surrounded by a membrane and is 20hm diameter .




>
two subunits combine in the cytoplasm
The site of protein synthesis -
ribosomes attached to the RER make

proteins that are excreted or attached to the cell membrane , ribosomes

that float free in the cytoplasm make proteins that stay in the


cytoplasm .




Rough Endoplasmic Reticulum
A system of membranes enclosing a fluid filled space The .
surface is
'




covered with ribosomes .
Its continuous with the nuclear membrane .
i



Folds and processes proteins that have been made at the ribosomes .




Smooth Endoplasmic Reticulum
Similar to
rough but
,
contains no ribosomes .
It synthesise and processes
lipids .

, vesicle
A small fluid filled sac in the cytoplasm ,
surrounded by a membrane .




Transports substances in and out of the cell , via the plasma membrane
and between organelles Some are .
formed by the golgi or ER
,
while others
,



are formed at the cell surface .




GolgiApparatus
A group of fluid filled -




,
membrane bound , flattened sacs Vesicles are often .




seen at the edges of the sacs : as secretory vesicles bring materials to and from it
It processes and packages new lipids and proteins . It also makes lysosomes .




'




MODIFICATION MAY INCLUDE >
adding Sugar >
glycoproteins found in MUCUS .




adding lipids Il pop rotten
> >



>
folding into 3D shape .




Mitochondrion
THE SITE OF AEROBIC RESPIRATION WHERE ,
ATP IS PRODUCED .




They are
usually oval shaped .


They have a double membrane -
the

inner one folded into structures called Cristal Inside
.
is the matrix , which

contains enzymes involved in respiration . ( The site of ATP production )
They can be spherical ,
dependant on the angle / plane they are viewed
at .




A proximately 2- 5pm long .




They are self replicating so more can be made it cells energy requires an

increase .
This means that they are abundant in cells with high metabolic

activity such as hier cells .
( many mitochondria is often an adaptation
of cells in mark schemes )