2.1 Structure and function of eukaryotic cells Flashcards
1
Q
What is the structure of a nucleus?
A
- contains hereditary material
- usually spherical
- between 10-20μm in diameter
2
Q
What is the function of the nucleus? (x4)
A
- controls the cells activities
- acts as the control centre through production of mRNA and tRNA for protein synthesis
- contains genetic information in the form of DNA and chromosomes
- makes ribosomal RNA and ribosomes
3
Q
What is the structure of the nuclear envelope?
A
- double membrane that surrounds the nucleus
- outer membrane is connected with endoplasmic reticulum and often has ribosomes on its surface
4
Q
What is the function of the nuclear envelope? (x2)
A
- controls what enters and exists the nucleus
- contains the reactions happening inside the nucleus
5
Q
What is the structure of the nuclear pores?
A
- 3000 pores in each nucleus
- 40-100nm in diameter
6
Q
What is the function of the nuclear pores?
A
- allows large molecules to pass through
7
Q
What is the structure of the nucleolus?
A
- small spherical region in nucleoplasm
8
Q
What is the function of the nucleolus? (x2)
A
- makes ribosomal RNA
- assembles ribosomes
9
Q
What is the structure of a chromosome?
A
- consists of protein bound, linear DNA
10
Q
What is the structure of the mitochondria?
A
- usually rod shaped
- 1-10μm in length
- surrounded by double membrane folded inner membrane forms cristae
- contain 70S ribosomes
11
Q
What is the function of the mitochondria?
A
- double membrane that controls what enters and leaves the mitochondrion
- produces ATP from respiration
12
Q
What is the structure of cristae?
A
- extensions of the inner membrane
- large surface area for respiration
(mitochondria)
13
Q
What is the structure of matrix?
A
- contains proteins, lipids, ribosomes, and DNA
14
Q
What is the function of matrix?
A
- controls production of the mitochondrion’s own proteins
(mitochondria)
15
Q
What is the structure of chloroplasts?
A
- usually disc-shaped
- 2-10μm in length
- double membrane (chloroplast envelope) that controls what enters and leaves the chloroplast
16
Q
How are the chloroplasts adapted to their function?
A
Chloroplasts contain both DNA and ribosomes so they can quickly and easily manufacture some of the proteins needed for photosynthesis.
17
Q
What is the structure of grana?
A
- stacks of up to 100 thylakoids
- thylakoids contain chlorophyll pigments
(chloroplast)
18
Q
What is the structure of stroma?
A
- fluid-filled matrix
- contains starch grains
(chloroplast)
19
Q
What is the function of chloroplasts?
A
- site of photosynthesis
- harvests sunlight
20
Q
What is the structure of the endoplasmic reticulum?
A
- system of sheet-like membranes in the cytoplasm
- it is continuous with the outer nuclear membrane
21
Q
What is the structure of the rough endoplasmic reticulum (RER)? (x2)
A
- ribosomes on the surface
- provides a large surface area for protein synthesis
22
Q
What is the structure of the smooth endoplasmic reticulum (SER)?
A
- more tubular and no ribosomes
23
Q
What is the function of RER?
A
- provide a pathway for transport of materials throughout the cell
- protein synthesis
24
Q
What is the function of SER?
A
- synthesises, stores and transports lipids and carbohydrates
25
What is the structure of the Golgi apparatus?
- looks similar to SER, but more compact
- it consists of a stack of membranes that make up flattened sacs, or cisternae, with small rounded hollow structures called vesicles
26
What is the function of the Golgi apparatus?
- receives proteins from the ER
- modifies them e.g. adding sugars
- packages them into vesicles to be transported around the cell or to outside the cell
27
What is the structure of lysosomes?
- produced by the Golgi body
- vesicles that contain enzymes that break things down
28
What is the function of lysosomes? (x4)
- they can hydrolyse material ingested by phagocytic cells
- release enzymes to the outside of the cell (exocytosis) in order to destroy material around the cell
- digest worn out organelles so that the useful chemicals they are made of can be reused
- completely break down cells after they have died (autolysis)
- digests contents of phagosome
- exocytosis of digestive enzymes
29
What is the structure of ribosomes?
- not surrounded by a membrane
- very small organelles in the cytoplasm and bound to rough ER
- consists of 2 subunits - 80s and 70s
30
Where are 80s ribosomes found?
- in eukaryotic cells
- (25nm in diameter)
31
Where are 70s ribosomes found?
- in prokaryotic cells, mitochondria and chloroplasts
- slightly smaller than 80s
32
What is the function of a ribosome?
- site of protein synthesis which acts as an assembly line to use mRNA to assemble proteins
33
What is the structure of a cell wall?
- made up of a number of polysaccharides such as cellulose
- have a thin layer called the middle lamella
34
What is the function of the cell wall?
- provide mechanical strength-stop individual cells from bursting and to provide structure to the plant
- movement of water - allows water to pass along it
35
What is the structure of a vacuole?
- fluid filled sack
- single membrane (tonoplast)
- contains mineral salts, sugars, amino acids, pigments and other molecules
36
What is the function of a vacuole?
- provide support to the plant
- can act as a temporary food store
- pigments may colour petals
37
What are the two types of ER?
- rough endoplasmic reticulum
- smooth endoplasmic reticulum
38
What is a eukaryotic cell?
- distinct nucleus
- membrane-bound organelles
39
What are vesicles?
Small structure within a cell, consisting of fluid enclosed by a lipid bilayer
40
What is a turgid plant cell?
Cell swells a bit but cell wall prevents lysis
41
Describe the structure and function of the cell surface membrane.
• Fluid mosaic phospholipid bilayer with extrinsic and intrinsic proteins embedded
• isolates cytoplasm from extracellular environment
• selectively permeable to regulate transport of substances
• involved in cell signalling/cell recognition
42
Explain the role of cholesterol, glycoproteins and glycolipids in the cell surface membrane.
cholesterol = steroid molecule connects phospholipids and reduces fluidity
glycoproteins = cell signalling, cell recognition and binding cells together
glycolipids = cell signalling and cell recognition
43
What are some common cell adaptation?
• folded membrane or microvilli increase surface area e.g. for diffusion
• many mitochondria = large amounts of ATP for active transport
• walls one cell thick to reduce distance of diffusion pathway
