A level Biology OCR A Module 6 summary notes
1). Describe the nucleus
Ans: -surrounded by nuclear envelope
- contains chromatin
-instructs for protein synthesis
2). Describe the nucleolus
Ans: Inside the nucleus
No membrane
Contains RNA
Where ribosomes are made
3). Describe the rough endoplasmic reticulum (rer)
Ans: -Membranes continuous with nuclear envelope
-fluid-filled cavities called cisternae
-Ribosomes attached
-Produce proteins
-A transport system
4). Describe the smooth endoplasmic reticulum (ser)
Ans: -membranes not continuous with nuclear membrane
-continuous with RER
-cisternae
-lipid enzymes
-absorption, synthesis and transport of lipids
-no ribosomes
5). Describe the golgi apparatus
Ans: -stack of membrane-bound flattened sacs
-modify proteins (e.g. add sugar to make glycoproteins)
-proteins packaged into vesicles
6). Describe lysosomes
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, Ans: -single membrane
-contain powerful hydrolytic enzymes
-Abundant in phagocytic cells
-can engulf old cell organelles
-keep enzymes separate from cell
7). Describe mitochondria
Ans: -double membrane
-inner membrane folded into cristae
-fluid-filled matrix
-self-replicating
-ATP production
-abundant in cells with lots of metabolic activity (muscle, liver etc.)
8). Describe chloroplasts
Ans: -double membrane
-only in plants
-thylakoids containing chlorophyll
-each thylakoid stack called a granum
-Stroma - fluid-filled matrix
-loops of DNA and starch grains
-site of photosynthesis
-Abundant in palisade mesophyll layer
9). Describe vacuole
Ans: -surrounded by tonoplast membrane
-contains water and solutes
-maintains stability (turgid when full)
-only in plants
10). What type of cell wall do plants have?
Ans: cellulose
11). What type of cell wall do bacteria have?
Ans: peptidoglycan
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, 12). What type of cell wall do fungi have?
Ans: chitin
13). Describe the cellulose cell wall
Ans: -outside plasma membrane
-bundles of cellulose fibres
-prevents cell from bursting when turgid
- strength and support
- maintains cell shape
-permeable
-only in plants
14). Describe cilia and undulipodia
Ans: -protrusions surrounded by cell membrane
-contains microtubules
-formed from centrioles
-nearly all cells have cilia containing receptors
15). What type of cell has cilia and why?
Ans: Epithelial cells have cilia to move mucus
16). What type of cell has undulipodium and why?
Ans: A sperm cell has a undulipodium to move
17). Describe ribosomes . what is the difference between the functions of free ribosomes and
rer ribosomes?
Ans: -no membrane
-made of ribosomal RNA
- made in nucleolus in two parts
-those bound to RER, synthesise proteins for use outside cell
- those free in cytoplasm, assemble proteins for use inside the cell
18). Describe the process of protein synthesis
Ans: mRNA made in nucleus (transcription)
mRNA leaves nucleus through pore and attaches to ribosome.
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, Ribosome assembles protein (translation)
Protein travels in vesicle which fuses with Golgi apparatus
Golgi apparatus modifies and packages protein.
Protein travels to and fuses with plasma membrane in a vesicle.
Plasma membrane opens up to release protein (exocytosis)
19). What are the three features of the cytoskeleton and what are their functions?
Ans: Microfilaments -mechanical strength
- support and shape
Microtubules - provide tracks for movement
- act as motors using ATP
-made of tubulin
Intermediate filaments - anchor nucleus within cytoplasm
-extend between cells enabling cell to cell signalling
All - work together to help cell move
20). Describe centrioles
Ans: Two bundles of microtubules at right angles to eachother. They are arranged to
form a cyclinder.
Forms the spindle before the cell divides
Also involved in formation of cilia and undulipodium
Usually only in animals
21). Describe the difference between features of prokaryotes and eukaryotes.
Ans: Prokaryotes (e.g. bacteria) - no nucleus
- 70s ribosomes not 80s (smaller)
-no centrioles
-no membrane-bound organelles
- different cell wall (peptidoglycan or chitin)
-naked DNA (in cytoplasm)
-plasmids
-waxy capsule
-flagella
-pili
22). What are the advantages of an optical microscope?
Ans: -relatively cheap
-easy to use
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1). Describe the nucleus
Ans: -surrounded by nuclear envelope
- contains chromatin
-instructs for protein synthesis
2). Describe the nucleolus
Ans: Inside the nucleus
No membrane
Contains RNA
Where ribosomes are made
3). Describe the rough endoplasmic reticulum (rer)
Ans: -Membranes continuous with nuclear envelope
-fluid-filled cavities called cisternae
-Ribosomes attached
-Produce proteins
-A transport system
4). Describe the smooth endoplasmic reticulum (ser)
Ans: -membranes not continuous with nuclear membrane
-continuous with RER
-cisternae
-lipid enzymes
-absorption, synthesis and transport of lipids
-no ribosomes
5). Describe the golgi apparatus
Ans: -stack of membrane-bound flattened sacs
-modify proteins (e.g. add sugar to make glycoproteins)
-proteins packaged into vesicles
6). Describe lysosomes
PaperStoc.com Page 1 of 46
, Ans: -single membrane
-contain powerful hydrolytic enzymes
-Abundant in phagocytic cells
-can engulf old cell organelles
-keep enzymes separate from cell
7). Describe mitochondria
Ans: -double membrane
-inner membrane folded into cristae
-fluid-filled matrix
-self-replicating
-ATP production
-abundant in cells with lots of metabolic activity (muscle, liver etc.)
8). Describe chloroplasts
Ans: -double membrane
-only in plants
-thylakoids containing chlorophyll
-each thylakoid stack called a granum
-Stroma - fluid-filled matrix
-loops of DNA and starch grains
-site of photosynthesis
-Abundant in palisade mesophyll layer
9). Describe vacuole
Ans: -surrounded by tonoplast membrane
-contains water and solutes
-maintains stability (turgid when full)
-only in plants
10). What type of cell wall do plants have?
Ans: cellulose
11). What type of cell wall do bacteria have?
Ans: peptidoglycan
PaperStoc.com Page 2 of 46
, 12). What type of cell wall do fungi have?
Ans: chitin
13). Describe the cellulose cell wall
Ans: -outside plasma membrane
-bundles of cellulose fibres
-prevents cell from bursting when turgid
- strength and support
- maintains cell shape
-permeable
-only in plants
14). Describe cilia and undulipodia
Ans: -protrusions surrounded by cell membrane
-contains microtubules
-formed from centrioles
-nearly all cells have cilia containing receptors
15). What type of cell has cilia and why?
Ans: Epithelial cells have cilia to move mucus
16). What type of cell has undulipodium and why?
Ans: A sperm cell has a undulipodium to move
17). Describe ribosomes . what is the difference between the functions of free ribosomes and
rer ribosomes?
Ans: -no membrane
-made of ribosomal RNA
- made in nucleolus in two parts
-those bound to RER, synthesise proteins for use outside cell
- those free in cytoplasm, assemble proteins for use inside the cell
18). Describe the process of protein synthesis
Ans: mRNA made in nucleus (transcription)
mRNA leaves nucleus through pore and attaches to ribosome.
PaperStoc.com Page 3 of 46
, Ribosome assembles protein (translation)
Protein travels in vesicle which fuses with Golgi apparatus
Golgi apparatus modifies and packages protein.
Protein travels to and fuses with plasma membrane in a vesicle.
Plasma membrane opens up to release protein (exocytosis)
19). What are the three features of the cytoskeleton and what are their functions?
Ans: Microfilaments -mechanical strength
- support and shape
Microtubules - provide tracks for movement
- act as motors using ATP
-made of tubulin
Intermediate filaments - anchor nucleus within cytoplasm
-extend between cells enabling cell to cell signalling
All - work together to help cell move
20). Describe centrioles
Ans: Two bundles of microtubules at right angles to eachother. They are arranged to
form a cyclinder.
Forms the spindle before the cell divides
Also involved in formation of cilia and undulipodium
Usually only in animals
21). Describe the difference between features of prokaryotes and eukaryotes.
Ans: Prokaryotes (e.g. bacteria) - no nucleus
- 70s ribosomes not 80s (smaller)
-no centrioles
-no membrane-bound organelles
- different cell wall (peptidoglycan or chitin)
-naked DNA (in cytoplasm)
-plasmids
-waxy capsule
-flagella
-pili
22). What are the advantages of an optical microscope?
Ans: -relatively cheap
-easy to use
PaperStoc.com Page 4 of 46
