Cells and Cell Transport Flashcards
1
Q
what are prokaryotes
A
very small single celled organisms with no nucleus and no membrane bound organelles in their cytoplasm.
2
Q
prokaryotes will always have? (5)
A
- a cell wall
- a cell surface membrane
- a circular DNA that’s free in the cytoplasm
- ribosomes
- cytoplasm
3
Q
prokaryotes might have? (3)
A
- a capsule surrounding the cell wall
- one or more plasmids
- one or more flagella
4
Q
what are eukaryotes
A
Single or multicellular organisms containing a nucleus a cytoplasm and other organelles
5
Q
differences between prokaryotes and eukaryotes
A
- prokaryotes have smaller 70s ribosomes , eukaryotes have bigger 80s ribosomes
- prokaryotes have no nucleus, eukaryotes do
- DNA is circular in prokaryotes, DNA is linear in eukaryotes
6
Q
similarities between prokaryotes and eukaryotes
A
- both have ribosomes
- both have a cell membrane
- both are alive
7
Q
what is binary fission
A
A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size
8
Q
function and structure of a nucleus
A
Contains the genetic material determining the development structure and function of the cell
-bound by a double membrane (a nuclear envelope) which has nuclear pores
9
Q
function and structure of ribosomes
A
-made of protein and ribosomal RNA
- site of protein synthesis
10
Q
structure of the endoplasmic reticulum
A
flattened membrane sacs which form an internal transport system in the cell
11
Q
smooth Endoplasmic reticulum function
A
-involved in the production and transport of lipids
12
Q
what are lysosomes
A
simple sacs containing hydrolytic enzymes surrounded by a single membrane formed by the Golgi apparatus
13
Q
lysosome’s function? (4)
A
- fuse with the vesicles during phagocytosis releasing hydrolytic enzymes which digest the material inside
- engulfs and digests non functioning organelles
- release of enzymes outside cell
- autolysis
14
Q
Rough Endoplasmic Reticulum function
A
- has ribosomes that produce secretory proteins which are sent to the Golgi apparatus for packaging and/or modification
15
Q
3 functions of the Golgi Apparatus
A
- adds carbohydrates to proteins received from RER to form glycoproteins
- packages proteins/glycoproteins into Golgi vesicles for secretion
- Produces lysosomes
16
Q
function of mitochondria
A
- involved in aerobic respiration which produces ATP
17
Q
Mitochondria structure
A
- bound by two membranes forming an envelope around an inner matrix
- the folds of the inner membrane = cristae
- matrix contains enzymes for respiration, also contains DNA and ribosomes
18
Q
function of chloroplast
A
Site of photosynthesis
19
Q
Chloroplast structure (4)
A
- flattened biconvex discs surrounded by an envelope consisting of two membranes
- flattened sacs called thylakoids form stacks called grana
- grana provides a large SA for the chlorophyll molecules
- membrane system is surrounded by the stroma which contains enzymes sugars and starch granules
20
Q
function of cell wall
A
Provides support, strength and shape to the cell
21
Q
Cell Wall Structure
A
-consists of cellulose microfibrils embedded in a matrix containing other polysaccharides
22
Q
Algae Cell Wall consists of? (3)
A
- cellulose
- glycoproteins
- a mixture of both
23
Q
Fungi Cell Wall contains? (3)
A
- chitin (nitrogen containing polysaccharide)
- glucan
- glycoproteins
24
Q
vacuole contains? (3)
A
- soluble sugars
- salts
- sometimes pigment
25
What is cell differentiation?
The process in which cells become specialized.
26
What are tissues?
-groups of similar cells which perform a specific function
27
What is an organ?
A group of different tissues that work together to perform a certain function.
28
What is an organ system?
A group of organs working together to perform a particular function
29
What is an organ system?
A group of organs working together to perform a particular function
30
What is an epithelial cell?
cells in the body specialised for the absorption or transport of important molecules
31
Intestine Epithelial cell adaptations? (2)
- folded cell surface membrane into microvilli to increase surface area
- numerous mitochondria to provide ATP for the release of energy. (active transport)
32
What is ultracentrifugation?
- centrifugation is a method used to separate structures of different density
33
Optimal conditions for UC (3)
- Isotonic solution as it prevents osmotic movement in or out of organelles
- Ice cold temperature to minimalize/ stop enzyme activity (preventing autolysis of the organelles)
- buffer solution to maintain the pH so the proteins aren't denatured
34
Describe the process of Ultracentrifugation
- cells are broken open by homogenising a tissue in optimal conditions using a blender
- resulting suspension may be filtered to remove cell debris eg. cell walls or unburst cells
- the homogenate is centrifuged at a low speed which makes the densest organelles form a pellet at the bottom
- the supernatant (the liquid remaining) is centrifuged again at a higher speed for longer where the 2nd densest organelles forms a pellet
- repeat process by increasing speed and duration of centrifugation of in order to get several other pellets
35
Order of pellet formation
-nuclei
-chloroplast( if plant cell)
-mitochondria
-endoplasmic reticulum
-ribosomes
36
In a light microscope the specimen must be?
-thin so that light passes through it and it is visible
-be stained in order to make structures visible
37
How does an electron microscope work?
It uses a beam of electrons which are focused using electromagnets.
38
Differences between Scanning Electron Microscope and Transmission Electron Microscope
- TEM has a higher resolution than SEM
- TEM produces images of internal structures, SEM produces images of external structures
- TEM gives 2d image, SEM gives 3d image
39
Similarities between Scanning Electron Microscope and Transmission Electron Microscope
- Both use electron beams focused by electromagnets
40
Advantage of electron microscope
-uses electrons which have a shorter wavelength and therefore greater resolution than light microscopes
-unlike electron microscopes, light microscopes get blurred at higher magnification
41
I AM equation?
Image size = Actual Size x Magnification
42
Why is the cell-surface membrane described as a fluid-mosaic?
- the phospholipid molecules in the bilayer are constantly moving about giving a fluid structure
- the protein molecules are unevenly distributed throughout the membrane forming a mosaic
43
How are phospholipids arranged in a membrane?
- hydrophilic heads of phospholipids oriented either inwards towards the cytoplasm or outwards towards the watery extra-cellular fluid
- hydrophobic tails are oriented towards each other away from water.
44
What passes through a membrane during simple diffusion?
-very small molecules e.g, carbon dioxide and oxygen
45
What does a phospholipid bilayer prevent from going through?
- water soluble ions and polar molecules
46
Cholesterol in the cell membrane does what?
- provides strength and regulates fluidity of fatty acid chain
47
Channel Proteins in the cell membrane does what?
- Helps molecules be transported through the membrane by Facilitated Diffusion
48
Carrier Proteins in the cell membrane does what?
- Helps molecules be transported through the membrane by facilitated Diffusion and active Transport
49
Glycoproteins and Glycolipids Function
involved in cell to cell recognition and able to act as receptors
50
Intrinsic and Extrinsic Protein
intrinsic - spans the whole membrane
extrinsic - doesn't span the whole membrane
51
What is diffusion?
- the net movement of molecules from a high concentration to a low concentration until the molecules are equally distributed
52
Rate of Diffusion equation (Fick's Law)
Surface Area x Concentration Difference/Diffusion Distance
53
What factors increase Rate of Diffusion?
Increased Surface Area
Increased Concentration Difference
Decreased Diffusion Distance
54
What is facilitated diffusion
- Diffusion aided by Carrier and Channel Proteins without the use of energy
55
What is Active Transport?
- the movement of ions or molecules across a cell membrane against the conc gradient through carrier proteins and requiring energy.
56
How do carrier proteins work?
- the carrier protein has a complementary shape to the polar molecule being transported
- they bind which causes the carrier protein to change shape and transport molecules across the membrane
57
Factors that decrease Active Transport
- Lowering of temperature
- Lack of Oxygen
- Metabolic and Respiratory Inhibitors
58
What is Osmosis?
Diffusion of water through a selectively permeable membrane
59
What is Water Potential?
The potential tendency of water molecules to leave a solution by osmosis
60
Cell turgor during osmosis?
- as water enters the cell, the vacuole enlarges and the vacuole, cytoplasm and cell membrane exert an outward turgor pressure on the cell wall
61
What happens to red blood cells in a hypertonic solution?
- the cell has a higher water potential than the solution so water moves out of the cell and into the solution which makes the cell shrivel and become flaccid.
62
What happens to red blood cells in a isotonic solution?
- the solution has the same water potential as the cell so there is no net movement of water.
63
What happens to red blood cells in a hypotonic solution?
- the cell has a lower water potential than the solution and so water moves into the cell which causes swelling and eventually bursting of the cell
