Cell structure extra Flashcards
(28 cards)
Nuclear membrane
3 points
1) Controls the exchange of materials in the intercellular and external environment
2) semi permeable
3) Formed from a Phospholipid bilayer which is constantly in motion and 10 nm
Cell wall
3 point
1) Offers structural support
2) This is provided by the polysaccharide cellulose in plants and peptidoglycan in bacterial cells and chitin in fungi
3) Permeable
What is the cytoplasm that connects the cytoplasm of neighbouring plant cells?
Plasmodesmata
What separates the nucleus from the rest of the cell?
The nuclear envelope which contains many pores
What do the nuclear pores allow to happen?
It allows mRNA and ribosomes to travel out of the nucleus as well as allowing enzymes and signalling molecules in
What is chromatin?
The genetic material of the cell
Mitochondria
3 points
1) Site for aerobic respiration
2) Surrounded by a double membrane with the inner membrane highly folded into cristae
3) Small circular pieces of DNA and ribosomes are also found in the matrix for replication
Why are cristae needed in the mitochondria?
It contains enzymes needed for aerobic respiration
Chloroplasts
4 points
1) Larger then mitochondria and surrounded by a double membrane
2) membrane bound compartments called thylakoids which contain chlorophyll and stack to form structures called grana held together by llamale
3) Site for photosynthesis
4) Contains small pieces of DNA and ribosomes to synthesise proteins for chloroplast replication and photosynthesis
What joins the thylakoids together?
Lamllele
Where does the light independent stage of photosynthesis take place?
Thylakoids
Where does the light independent stage of photosynthesis take place?
Stroma
Ribosome
6 points
1) Found in the cytoplasm/ RER
2) Each ribosome is a complex of rRNA and proteins
3) Site of translation
4) Formed in the nucleolus
5) In eukaryotes they are 80s in prokaryotes they are 70s
6) Do not have a membrane
RER
3 points
1) Surface covered in ribosomes
2) Formed from continuous folds of membrane continuous with the nuclear envelope
3) Processes proteins made by ribosomes
SER
2 points
1) No ribosomes
2) Involved in the production, processing and storage of lipids, carbohydrates and steroids
synthesizes lipids
Golgi Apparatus
2 points
1) Flattened stacks of membrane
2) Modifies proteins and packages them into vesicles and lysosomes
Vacuole
3 points
1) Sac in plant cells surrounded by tonoplast
2) Semi permeable membrane
3) Vacuoles in animal cells are non permanent and small
4) Controls pressure
5) absorbs and hydrolyses potentially harmful substances within the cytoplasm
Lysosomes
3 points
1) Specialist forms of vesicles which contain hydrolytic enzymes
2) Break down waste material such as worn out organelles
3) Used extensively by cells of the immune system and in apoptosis ( cell death)
What are hydrolytic enzymes?
Enzymes that break down biological molecules
Vesicle
Membrane bound sac used for transportation and storage
Centriole
3 points
1) Hollow fibres made from microtubules
2) Two centrioles at right angles to each other form a centrosome, which organises the cell during cell division
3) Not found in flowering plants/ fungi
Microtubules
2 points
1) Make up the cytoskeleton of a cell
2) Made of tubulin combined to form dimers, the dimers then combine to form protofilaments
How big are microtubules?
about 25 nm in diameter
How many protofilaments make up a microtubule?
13 in a cylinder
