cells Flashcards
(111 cards)
1
Q
what is the the function of the golgi apparatus?
A
processes and prepares proteins and lipids for use
2
Q
what is function of the rough endoplasmic reticulum?
A
site of protein and glycoprotein synthesis. bits of membrane pinch off to form vesicles (sacs) which carry protein away from RER
3
Q
what is the function of the smooth endoplasmic reticulum?
A
makes substances and stores lipids, in skeletal muscle it can store calcium ions etc, in endocrine glands it contains enzymes that break down harmful substances
4
Q
what is the function of a lysosome?
A
uses enzymes to breakdown foreign matter and dead cells
5
Q
what is the function of peroxisomes?
A
use oxygen to break down poisons
6
Q
what is the function of centrosome?
A
organises chromosomes before cell division
7
Q
what is the function of centriole?
A
determines where the nucleus and other organelles within the cell are located.
8
Q
what is the function of a cell vacuole?
A
maintains osmotic pressure in cell,
makes sure plant stays turgid,
stores unwanted chemicals
9
Q
where does photosynthesis happen in a light dependent reaction?
A
thylakoid membrane
10
Q
Where does photosynthesis happen in light independent reaction?
A
The stroma
11
Q
What is the structure of the chloroplast?
A
-double membrane surrounds the stroma
-Fluid filled sacs called thylakoids (stacked to form grana)
-Thin pieces of thylakoid membrane called lamellae link grana together
-thylakoid membrane contain photosynthetic pigment
12
Q
What is the function of the chloroplast?
A
Photosynthesis via light dependent/ independent reactions
13
Q
What is the structure of the cell wall?
A
-Rigid structure
- plants and algae cell wall- cellulose
- fungal cells- chitin
14
Q
Function of cell wall?
A
-Help maintain cell shape by providing structural shape
- provides protection against invading pathogens
15
Q
Structure of a permanent cell vacuole?
A
-Pocket of cell sap, solution of sugars, salt and water
-surround by a membrane called tonoplast
16
Q
Structure of the Golgi complex?
A
-Made up of Golgi apparatus and several small vesicles
-membrane bound, fluid filled channel like structure
-vesicles are detached fluids like pockets
17
Q
Structure of the lysosome?
A
-Type of Golgi vesicles
-surrounded by a membrane containing lysozymes
-the PH inside lysosomes is acidic
18
Q
Structure of rough endoplasmic reticulum
A
-studded with ribosomes
- network of channel like structures filled with fluid
-linked to nuclear membrane by small tubules
-large surface area
19
Q
Structure of smooth endoplasmic reticulum
A
- network of channel like structures filled with fluid
-linked to nuclear membrane by all tubules
-large surface area
20
Q
Structure of the nucleus
A
-double membrane (nuclear envelope)
- DNA, rRNA and proteins are contained in the nucleus
- DNA and proteins are wound tightly to form chromosomes
21
Q
Function of the nucleus
A
-contains the DNA
-controls gene expression and protein synthesis
- protein synthesis and ribosome production
22
Q
Function of the nucleus
A
-contains the DNA
-controls gene expression and protein synthesis
- protein synthesis and ribosome production
23
Q
Structure of the cell membrane
A
-Made up of lipids and proteins
-hydrophilic heads—> inner and outer surfaces of membrane
-hydrophobic tails—> middle of membrane
24
Q
Function of the cell membrane
A
Controls what enters and exits the cell
Partially permeable
25
Structure of mitochondria
-double membrane
-inner membrane is highly folded and forms cristae=large SA
-inner matrix contains enzymes involved in respiration
26
Function of mitochondria
-Where respiration takes place and aerobic energy is produced
- collects ATP for energy
27
Structure of the ribosomes
-single membrane
- very small structure with large subunit and small subunit
-Consists of ribosomal proteins and rRNA
-float freely in cytoplasm
28
Function of ribosomes
Where protein synthesis takes place
29
What does cristae do in the mitochondria
-Extensions of the inner membrane
-provide large SA for attachment of enzymes and other proteins in respiration
30
What does the matrix do in the mitochondria?
-makes up remainder of mitochondria
-contains proteins,lipids, ribosomes, DNA that allows mitochondria to control production of some of their own proteins
31
What is the chloroplast envelope?
-double plasma membrane that surrounds the organelle
-highly selective of what they allow in and out
32
What is the grana in the chloroplast?
Stacks of up to 100 disk like structure called thylakoids. Where the 1st stage of photosynthesis takes place
33
What is the stroma in the chloroplast?
A fluid filled matrix where the 2nd stage of photosynthesis takes place
34
What is a nuclear envelope?
Double layered structure consisting of 2 adjacent membranes, 40-70nm apart
Envelope is perforated by pores, 50-70nm in diameter
35
Why does the nuclear envelope have pores?
In order to communicate between nucleus and cytoplasm
36
What is chromatin in the nucleus?
Granular appearance of hereditary material in non-dividing cells
37
What is the nucleoplasm in the nucleus?
Granular jelly like material that makes up the nucleus
38
What is resolution?
The ability for a microscope to distinguish between 2 points which are close together
39
differences between light and electron microscopes?
Light microscope:
Lower resolution
Lower magnification
Cheap
Uses light to form image
Coloured
2d
Electron microscope:
High magnification
High resolution
Black and white
Expensive
Specimens must be dead
3d
40
Differences between transmission electron microscope and scanning electron microscope?
Transmission electron microscope:
Electron beam passed through simple sample
Electrons pass through dense parts less easily
Image is 2d
Magnification= 500,000
Scanning electron microscope:
Electrons don’t pass through specimens
Bounces off specimen
3d view
Magnification= 100,000
41
What is a prokaryotic cell?
Single celled organisms of a without a nucleus and no membrane bound organelles
42
Difference between prokaryotic and eukaryotic cell?
Prokaryotic:
- may have flagella
- small ribosomes
- DNA held on linear chromosomes
Eukaryotic:
- cellulose based cell wall
- large (70s) ribosomes
-DNA located within nucleus and held on circular chromosomes
43
What is the function of circular chromosomes? (Mesosomes)
help in the synthesis of the cell membrane, replication of DNA, and protein synthesis
44
What is the function of slime capsule?
Helps protect the bacteria from attack by cells of immune system
45
Function of the pili?
Help prokaryotes stick to other cells and can be used in the transfer of genetic material
46
Function of plasmids?
Small loops of DNA which contains genes for factors such as antibiotic resistance
47
What is the process of binary fission?
1) circular DNA
2) the cell gets bigger and DNA moves to opposite poles of the cell
3) cytoplasm begins to divide and new cell starts to form
4) 2 daughter cells are produced. Each daughter cell has one copy of circular DNA but variable numbers of copies of plasmids
48
What are the 3 main general structural points of a virus?
Attachment proteins
Core of genetic material
Capsid (protein coat)
49
What are the 3 main general structural points of a virus?
Attachment proteins
Core of genetic material
Capsid (protein coat)
50
How to calculate the logarithm of the no. Of bacteria?
Log(1)=0
51
What are the steps of viral replication by host cell?
1) virus attaches to host cell by receptor proteins
2) genetic material is released into host cell
3) genetic material and proteins are replicated by host cell ‘machinery’
4) viral components assemble
5) replicated viruses released from host cell
52
What is cell fractionation?
Process where cells are broken up and the different organelles are separated
53
Where does the tissue need to be placed before cell fractionation?
Cold buffered solution
54
Why does it need to be a cold buffered solution? (Cell fractionation)
Cold- reduce enzyme activity that may breakdown cells
Same water potential as tissue- prevents organelles bursting/shrinking
Buffered- to keep pH the same
55
3 steps of stage one in cell fractionation?
-cells broken by homogeniser (blender)
-releases organelles from cell
-resultant fluid (homogenate) filtered to remove cells and debris
56
Stage 2 of cell fractionation (ultracentrifugation)?
Process by which fragments in the filtered homogenate are separated by a machine called a centrifuge
57
What is centrifugation?
Separates cells components on the basis of size and density
Larger+denser=greatest centrifugal force and move rapidly
Smaller+less dense= remain in the suspension above (supernatant)
58
What is differential centrifugation?
Repeated centrifugation will progressively fractionate cell homogenates into their components
59
What is in pellet 1 of ultracentrifugation?
Whole cells
Nuclei
Cytoskeletons
60
What is in pellet 2 of ultracentrifugation?
Mitochondria
Peroxisomes
61
What is in pellet 3 of ultracentrifugation?
Microsomes
Lysosomes
Small vesicles
62
What is in pellet 1 of ultracentrifugation?
Ribosomes
Viruses
Large macromolecules
63
How to isolate chloroplasts from a sample of leave tissue?
1) use a pestle and motor to grind up leaf along with 20cm3 of isolation solution
2) filter the liquid through a muslin cloth into a beaker
3) transfer the liquid to centrifuge tubes and centrifuge them at high speed for 8 mins
4) chloroplasts will gather in the bottom of a tube in a pellet
64
What is the fluid mosaic model of plasma membranes?
A model describing the structure of cell membranes as a mosaic of various components, including phospholipids and proteins
65
What is the width of the fluid mosaic model?
7 nm wide
66
What is one function of membranes covering the surface of every cell?
Keeping cellular components inside the cell
67
What is another function of plasma membranes?
Allowing selected molecules to move in and out of the cell
68
How do membranes isolate organelles?
By separating them from the rest of the cytoplasm
69
What role do membranes play in cellular processes?
Allowing cellular processes to occur separately
70
What is one site of biochemical reactions in cells?
The plasma membrane
71
What property allows a cell to change shape?
The flexibility of the plasma membrane
72
What are the two parts of phospholipids?
Hydrophilic heads and hydrophobic tails
73
Fill in the blank: Phospholipids have ______ heads and ______ tails.
hydrophilic, hydrophobic
74
What do hydrophilic heads of phospholipids interact with?
Water
75
What do hydrophobic tails of phospholipids do?
Point away from water
76
What are the components of phospholipids?
Phosphate and fatty acids
77
What are intrinsic proteins?
Intrinsic proteins span the whole width of the membrane.
78
What are extrinsic proteins?
Extrinsic proteins are confined to the inner or outer surface of the membrane.
79
Where can extrinsic proteins be found?
They may be free on the membrane surface or bound to intrinsic proteins.
80
What is one function of extrinsic proteins on the extracellular side?
Receptors for hormones or neurotransmitters, or involved in cell recognition.
81
What are many extrinsic proteins classified as?
Glycoproteins.
82
What is a function of extrinsic proteins on the cytosolic side?
Cell signaling or chemical reactions.
83
What role does cholesterol play in the membrane?
Cholesterol keeps the membrane stable at normal body temperature.
84
What can happen to cells without cholesterol?
Cells may burst.
85
What is the function of phospholipids in the membrane?
They act as a barrier to most substances, helping regulate what enters and exits the cell.
86
How does the size and polarity of a molecule affect its diffusion across the membrane?
Smaller and less polar molecules diffuse faster and easier.
87
Give an example of a small, non-polar molecule that rapidly diffuses across the membrane.
Carbon dioxide or oxygen.
88
Give an example of a small, polar molecule that can diffuse but slower.
Water or urea.
89
what did the Gorter and Grendel model of membrane in 1920s suggest?
phospholipids in membrane arranged tail to tail in bilayer
90
what were the issues with Gorter and Grendel's model of membrane?
did not explain presence of proteins of plasma membrane
did not explain how insoluble molecules moved in and out of cell.
91
what did the Davson-Danielli model of membrane in 1930's suggest?
a lipid protein sandwich
92
limitations of Davson- Danielli model?
did not explain presence of proteins inside membrane
93
what did the Singer ad Nicolson model in the 1970's suggest about the membrane?
they were fluid and proteins were both integral and peripheral.
explained proteins throughout the membrane
supported freeze frames
biochem experi showed proteins moving
94
What is a vaccine and how do they work
Suspension of antigens that are put into body to induce artificial active immunity
Antibodies released by plasma cells
Long term immunity because memory cells are produced
95
Strengths of vaccinations
Lifetime protection
Harmless
96
Limitations of vaccinations
Poor responses
Antigenic variation- causes vaccines not to trigger response as too many antigens in cell surface- vaccine too slow
Antigenic concealment- pathogen hides from immune system by living in cells or coats body with host proteins
97
Herd immunity
When a large population has been vaccinated so pathogen won’t spread
Unvaccinated are unlikely to contract it as disease levels are low
98
Inactivated vaccines
Contain whole pathogen-killed
Don’t trigger strong long lasting response, needs repeated doses
Allergic or local reactions
99
Live attenuated vaccines
Contain whole pathogens- weakened
Multiply slowly so body can recognise and trigger primary immune response
Strong long lasting response
Unsuitable for weak immune systems as pathogens may divide faster than antibodies
100
Therapeutic uses of monoclonal antibodies
Rabies treatment
Autoimmune therapies- monoclonal antibodies bind and deactivate factors involved in inflammatory diseases
Treatment for breast cancer- antibody receptor cells bind to them so they can be recognised and destroyed
101
How do scientists overcome that monoclonal antibodies are produced by animals
Genetically modified antibody chains so amino acid sequences are human
Alternating type and position of sugar groups attached to heavy polypeptide chains to reflect human ones
102
Diagnostic uses of monoclonal antibodies
-pregnancy test
-hiv
-cancer cells
103
Diagnostic uses of monoclonal antibodies
-pregnancy test
-hiv
-cancer cells
104
How to use monoclonal antibodies to detect blood clots (can be adapted)
Inject a mouse with fibrin (protein in clots)
Activates plasma cells to produce antibodies
Collected from mouse spleen
Plasma cells fused with tumour cells forming hybridomas
(Gamma rays binded so pathogens are labelled and found by gamma ray camera)
105
How to detect HIV
Monoclonal antibodies used
HIV antigen attached to test plate
Blood sample is passed over test plate if HIV antigens are present they bind to the antigen. Plate is washed
Monoclonal antibodies passed over plate, bind if present
Monoclonal antibody binded to enzyme
Bound MA is proportional to bound HIV, dye passed over plate
Enzyme catalysed colour change in dye substrate
106
What are elisa tests
Enzyme attached to antibody
When enzyme reacts with certain substrate, coloured product formed
Colour change= present
107
Direct elisa test
Single antibody that is complementary to antigen tested for
108
Indirect Elisa test
HIV antigens are bound to bottom of reaction vessel
Blood plasma from patient added to reaction vessel
HIV specific antibodies present in blood plasma bind to HIV antigens (primary)
Other antibodies in plasma are unbound and washed out
Secondary antibody with enzyme attached is added to vessel
Secondary antibodies bind to primary antibodies. Reaction vessel is washed out to remove unbound secondary (avoids false positives)
Solution is added that contains a substrate that reacts with enzyme attached to 2nd antibody
If secondary antibodies are present then a coloured product is produced which means hiv is present
109
Process of phagocytosis
Chemicals released by pathogens and body cells while under attack attract pathogens
Phagocytes find and identify pathogens by pathogenic antigens or receptor proteins - show antigens are non self
Phagocytes attach to pathogen by binding to its antigens then cell surface membrane surrounds and engulfs into phagocytic vacuole
Phagocytic vacuole fuses with lysosome- phagolysosome
Lysosome released lysozymes to digest pathogen
Products of pathogen displayed on cell surface of phagocytes for immune response
110
What are phagocytes
White blood cells that are produces continuously in bone marrow
111
2 main types of phagocytes
Neutrophils- can ingest microorganisms
Macrophages- eliminating diseased and damaged cells
