AO1 - Unit 2 Flashcards
1
Q
All cells arise from other ______________
A
cells
2
Q
Prokaryotic cells form new cells by ______________ _______________
A
binary fission
3
Q
Name two types of cell division.
A
mitosis and meiosis
4
Q
What is the role of the cell surface membrane?
A
Selectively permeable to control the exchange of material
5
Q
Give two types of molecule found in plasma membranes.
A
phospholipids, proteins
6
Q
Which type of cell has internal membranes?
A
eukaryotic cell
7
Q
What is the role of the nucleus?
A
stores DNA in the form of chromatin
8
Q
What is the role of the nucleolus?
A
makes ribosomes
9
Q
What is the role of chloroplasts?
A
absorb light energy for photosynthesis
10
Q
Where are chloroplasts found?
A
plants and algae
11
Q
What is role of Golgi apparatus?
A
modifies and packages proteins, adds carbohydrates to form glycoproteins
12
Q
What type of cell will have a lot of Golgi apparatus?
A
cells which secrete proteins or glycoproteins such as beta cells of the islets of langerhans
13
Q
What is the role of lysosomes?
A
contain lysosymes which hydrolyse pathogens or worn out organelles
14
Q
What is the difference between RER and SER?
A
rough contains ribosomes on surface, smooth does not
15
Q
What is the role of the RER?
A
transports proteins made at ribosomes
16
Q
What is the role of the SER?
A
synthesise, store and secrete lipids
17
Q
What type of cell have a cell wall?
A
prokaryotes and some eukaryotes - plants, fungi
18
Q
Eukaryotic cells undergo what to become suited to a particular job?
A
differentiation/specialisation
19
Q
Name a cell that has microvilli.
A
epithelial cells of the ileum
20
Q
Where are cristae found?
A
mitochondria
21
Q
What is the role of the cell vacuole?
A
storage of water/sugars needed for growth, waste disposal and turgidity
22
Q
Give 4 differences between prokaryotic and eukaryotic cells.
A
linear DNA vs circular DNA / nucleus vs no nucleus / membrane bound organelles vs none (like mitochondria, chloroplast, golgi body) / 80S ribosomes vs 70S ribosomes
23
Q
What type of cell has a plasmid?
A
prokaryotes / bacteria
24
Q
What type of particle is described as acellular and non-living?
A
virus
25
What stain is used to locate starch grains in a plant cell?
iodine
26
How is magnification calculated?
magnification = image size / actual size
27
How many micrometres in a mm?
1000
28
What is resolution?
minimum distance two objects can be seen to be distinct from one another
29
Explain why electron microscope has a greater resolving power than optical microscope.
shorter wavelength of electrons
30
In microscopy, what is an artefact?
something introduced to the image during preperation, excess stain for example, which is not naturally there
31
What is cell fractionation used for?
separate out organelles for study
32
What is homogenisation?
blending or breaking open cells to release contents
33
Give 3 properties of the solution used to homogenise the tissue
isotonic, ice cold and pH buffered
34
Why is the mixture filtered after homogenisation?
remove any debris which may have similar mass to organelles
35
Why do organelles separate out during centrifugation?
based on mass - heavier will go to bottom at lower speeds
36
After centrifugation what is left at the bottom of the tube?
pellet - heaviest organelles first
37
What do we call the fluid above it?
supernatant
38
In what order will organelles separate out?
nucleus, mitochondria/chloroplast, lysosomes, endoplasmic reticulum, ribosomes
39
During which stage of the cell cycle does DNA replication occur?
interphase - S phase
40
Which part of the cell cycle produces 2 identical daughter cells?
mitosis
41
How would you describe DNA replication?
semi-conservative
42
Where do centromeres attach during mitosis?
spindle
43
Name the stages of mitosis
prophase, metaphase, anaphase, telophase
44
What is cytokinesis?
seperation of the cell membranes to create two daughter cells
45
What leads to the formation of tumours and cancers?
uncontrolled mitosis
46
Many cancer treatments target what?
DNA synthesis in interphase of rapidly dividing cells
47
Do viruses undergo cell division?
no, they invade and reproduce inside other cells
48
Why are root tips used to study mitosis?
lots of mitosis occuring in growing tip, more likely to see each stage
49
How is mitotic index calculated?
number of cells in mitosis/total number of cells observed
50
Name a stain used to stain chromosomes?
giemsa
51
What is binary fission?
bacteria dividing from one parent cell to two daughter cells
52
Do plasmids replicate in binary fission?
yes, can be lots of times
53
Are internal membranes the same structure as the plasma membrane?
yes
54
How is membrane structure described?
fluid mosaic model / phospholipid bilayer with embedded proteins and glycoproteins
55
How do small lipid soluble substances cross the membrane?
simple diffusion
56
How does facilitated diffusion differ from simple diffusion?
carrier or channel proteins needed
57
What is osmosis?
movement of water across a partially permeable membrane from an area of high water potential to low water potential
58
What is a hypertonic solution?
solution that has a lower water potential than the cell
59
What is a hypotonic solution?
solution that has a higher water potential than the cell
60
What is an isotonic solution?
solution that has the same water potential than the cell
61
What is active transport?
movement of particles against the concentration gradient (low to high concentration) using a carrier protein and ATP for energy
62
What provides the energy for active transport?
ATP hydrolysis
63
How is Active transport similar to facilitated diffusion?
both use transport proteins
64
How is Active transport different to facilitated diffusion?
AT against the conc.grad and uses ATP (energy) whereas FD is passive and down the conc.grad
65
When is Active transport reduced or stopped?
when ATP can no longer be hydrolysed or transport proteins are saturated
66
Give an example of where co-transport occurs?
ileum of the small intestine
67
How are cells adapted for rapid transport of substances?
lots of mitochondria, microvilli, lots of carrier/channel proteins
68
What is a calibration curve?
general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration.
69
What is a calibration curve used for?
general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration.
70
When investigating water potential why is % change often used?
allows comparisons, tissues may have different starting masses
71
What is an antigen?
foreign protein that stimulates an immune response
72
What is a pathogen?
microorganism that causes harm to /infects a host
73
What 4 things can induce an immune response?
foreign cells, pathogens, cancer cells, abnormal cells, APC
74
What is a phagocyte?
a type of white blood cell which carries out phagocytosis
75
What are lysozymes?
hydrolytic enzymes found in lysosomes
76
What is antigenic variation?
change in the shape of the protein antigen of pathogens due to mutation
77
What leads to antigenic variability?
mutations
78
What is a capsid?
virus's protein coat
79
What is the cellular response?
immune response lead by T cells
80
Give 2 examples of non-specific immunity
phagocytosis, chemical barriers such as stomach acid and physical barriers such as skin
81
What does active immunity involve?
production of antibodies
82
How are antibodies described?
proteins with a quaternery structure of 4 polypeptide chains held together with disulphide bridges
83
What is an antigen presenting cell?
a cells which displays the antigens of a digested pathogen on its surface - after phagocytosis
84
What detects antigen presenting cells?
specific T cells and B cells
85
Once stimulated helper T cells stimulate which other cells?
phagocytes, cytotoxic T cells and B cells
86
Once stimulated how do B cells divide?
mitosis / clonal selection
87
What is formed when B cells multiply?
plasma cells and some memory cells
88
Which type of cell secretes antibodies?
plasma cells
89
Antibodies carry out what type of immune response?
humoral response
90
Which type of cell carries out the cellular immune response?
T cells
91
How do cytotoxic cells work?
T cells which destroy an infected cell directly by releasing perforin/hydrogen peroxide which punctures the cell membrane
92
What is passive immunity?
immunity required by acquiring antibodies
93
Give a disadvantage of passive immunity
not as long lasting as active immunity
94
Give an example of passive immunity
antibodies passed via breast milk
95
How does the secondary immune response differ from the primary immune response?
quicker increase in concentration of antibodies and higher concentrations of antibodies
96
What are monoclonal antibodies?
antibodies with the same tertiary structure specific to one type of antigen
97
Give 2 uses of monoclonal antibodies
cancer treatment / pregnancy tests
98
What is herd immunity?
when a high enough proportion of individuals in a population are immune (through vaccination) those who are not are still protected
99
Name 3 things a vaccine may contain
attenuated pathogen, antigens, toxins
100
What does HIV stand for?
human immunodeficiency virus
101
What type of microorganism is HIV?
retro virus
102
What does HIV contain?
RNA, proteins such as reverse transcriptase, lipid envelope, capsid and attachment proteins
103
What is role of reverse transcriptase?
make copies of DNA from RNA
104
What type of cell is infected by HIV?
Helper T cells
105
What does HIV infection lead to after a latent period?
reduced TH cell count, reduced immune system and therefore increased susceptibility to infection
106
What does ELISA stand for?
Enzyme Linked Immunosorbant Assay
107
what are the two types of ELISA?
direct and indirect ELISA
108
What does a labelled antibody look like
