Module 2 Flashcards
1
Q
what does a TEM do?
A
electrons transmitted through specimen and focused to create a 2D image
2
Q
what does an SEM do?
A
electrons sent across surface and reflected ones collected. lower resolution, but makes 3D images
3
Q
what is an artefact?
A
a visible structural detail caused by processing of the specimen
4
Q
where are ribosomes produced?
A
nucleolus
5
Q
describe the structure of the mitochondria
A
double membrane, inner membrane is folded to form cristae, interior fluid called cristae. Has its own DNA
6
Q
what does the cytoskeleton do?
A
maintains shape and stability of cell. Holds organelles in place, and causes movement of cell/organelle
7
Q
what is the cytoskeleton made of?
A
Microfilaments for cell movement and cytokinesis,
Microtubules, can move organelles and creates spindle fibres
Intermediate fibres for mechanical strength
8
Q
what arrangement do flagella and cilia have?
A
9+2 arrangement
9
Q
what do cilia do?
A
Beat in a rhythmic manner to create a current to move things
10
Q
what does SER do?
A
lipid and carbohydrate synthesis, and storage
11
Q
what does RER do?
A
synthesis and transport of proteins, has ribosomes
12
Q
where can you find ribosomes?
A
free in cytoplasm, on RER, in mitochondria, in chloroplasts
13
Q
Describe the process of releasing proteins from the cell
A
proteins synthesized on RER
packaged into transport vesicles
move towards Golgi via vesicles
vesicles fuse with Golgi
proteins structurally modified by Golgi
proteins travel to cell surface membrane via vesicles
vesicles fuse with membrane and proteins released by exocytosis
14
Q
what does the Golgi apparatus do?
A
modifying proteins and ‘packaging’ them into vesicles
15
Q
describe cellulose cell wall function
A
gives shape, defense mechanism, and supports both cell and plant when membrane presses against it
16
Q
what is the function of the vacuole?
A
generate turgor pressure
17
Q
how is DNA stored in prokaryotes?
A
free, in one supercoiled chromosome
18
Q
what are prokaryotic cell walls made of?
A
peptigoglycan
19
Q
describe differences in ribosome sizes
A
eukaryotes have 80S, prokaryotes have 70S
20
Q
which biological molecules contain nitrogen?
A
proteins and nucleic acids
21
Q
what elements do lipids and carbohydrates contain
A
carbon, oxygen, hydrogen
22
Q
what are polar molecules?
A
molecules with regions of negativity and positivity
23
Q
describe the properties of water
A
High boiling point
ice is less dense than water, so floats
adhesion and cohesion
high specific heat capacity
24
Q
describe how being a solvent makes water useful
A
acts as a medium for reactions, and can transport dissolved compounds
25
why is water a good transport medium?
due to capilliary action, and as it is a solvent
26
why is water being a coolant helpful?
because it can help maintain a constant temperature in an environment due to its high specific heat capacity, allowing enzyme controlled reactions to occur
27
why is water a good environment for fish to live in?
Because it is very stable. ice floats and creates an insulating layer to maintain stable temperature. the surface tension can also hold some insects
28
what is sucrose made of?
glucose and fructose
29
what is maltose made of ?
two alpha glucose
30
what is lactose made of?
galactose and glucose
31
what is starch made of?
amylose and amylopectin
32
describe the structure of amylose
many alpha glucose joined by 1-4 bonds, creating a helix which more is compact and less soluble than the glucose used to make it
33
describe the structure of amylopectin
mostly 1-4 bonds, but some 1-6 bonds that causes branching. this makes it very compact, and free ends mean glucose can be quickly added/removed.
34
is glycogen structurally similar to amylose or amylopectin
amylopectin, but with even more branches
35
how is cellulose formed?
with alternating alpha glucose molecules, creating a straight chain. cellulose is insoluble
36
how do you test for reducing sugars?
add sample and benedicts reagent
mix and heat in boiling water for 5 mins
should turn red
37
how to test for non reducing sugars?
boil sucrose(most common one) with HCl, will break down into fructose and glucose, both reducing sugars
38
how do you test for starch?
iodine solution will turn blue/black
39
why don't lipids and water mix?
lipids are non polar
40
what are the bonds between glycerol and fatty acids called?
ester bonds
41
what's the difference between saturated and unsaturated fats?
saturated have no carbon double bonds, whereas unsaturated have some, causing 'kinks'. these mean they can't pack as tightly, so are likely to be oils.
42
describe the structure of a phospholipid
charged phosphate head replaces a fatty acid chain.
43
what is a sterol?
a lipid that has a polar(hydrophilic) -OH group and the rest of the molecule is hydrophobic
44
list 8 lipid roles
```
membrane formation
energy storage
electrical insulation
thermal insulation
cushioning for vital organa
hormone production
waterproofing
buoyancy
```
45
how do you test for lipids?
mix with water, then ethanol, and shake. look for white emulsion on the top
46
what is the bond between two amino acids called?
peptide bond
47
what is an amino acid chain called?
polypeptide
48
describe the primary structure of proteins
the sequence in which amino acids are joined
49
describe the secondary structure of proteins
hydrogen bonds may form within amino acid chain, pulling it into an alpha helix shape. they can also form a beta-pleated sheet.
50
describe the tertiary structure of proteins
the folding of proteins into its final shape
51
what interactions between R-groups can occur in the tertiary structure?
hydrophilic/phobic
hydrogen bonds
ionic bonds
disulfide bridges, only in cysteine
52
describe the quaternary structure of proteins
association of additional proteins called subunits
53
which R-groups will be on the inside/outside of proteins
hydrophilic ones will be on the outside and hydrophobic on the inside, because the are made in the aqueous cytosol
54
what is a globular protein?
a compact, water soluble protein that is roughly spherical.
55
what type of protein is insulin?
Globular protein. being water soluble helps it be transported in the blood
56
what is a conjugated protein?
a protein with a non protein prosthetic group.
57
what type of protein is hemoglobin?
conjugated protein
58
what type of protein is catalase (not enzyme)
conjugated protein
59
what are fibrous proteins?
long, insoluble molecules. They are very organized, and not folded
60
describe the structure of keratin
fibrous protein in hair, skin and nails. Has lots of cysteine, causing disulfide bridges. more disulfide bridges= tougher material
61
what is elastin?
fibrous protein found in blood vessels and alveoli. can freely stretch, and cause elastic recoil
62
what is collagen?
fibrous protein found in skin, tendons, ligaments and nervous system. used as a connective tissue.
63
what is a nucleotide made of?
pentose sugar
phosphate group
nitrogenous base
64
how are nucleotides joined together?
nucleotides are joined to form polynucleotides by phosphodiester bonds.
65
what are pyrimidines?
the smaller bases, Thymine and Cytosine
66
what are purines?
The bigger bases, Adenine and Guanine
67
what does antiparallel mean?
The two strands run in opposite directions
68
what type of base is Uracil
pyrimidine (replaces Thymine)
69
describe DNA replication
DNA Helicase unzips DNA by breaking H bonds
Free DNA nucleotides pair up with the complimentary base pairs by forming hydrogen bonds
The new nucleotides are joined by DNA polymerase via phosphodiester bonds
One strand is new and one is old, and so is called semi-conservative replication
70
what is a gene?
The section of DNA that codes for a whole protein
71
what does it mean for the genetic code to be universal?
It is the same for all organisms
72
What does it mean for the genetic code to be degenerate?
Multiple codons can code for the same amino acid
73
describe the process of transcription
DNA is 'unzipped' by DNA Helicase
Free RNA nucleotides base pair with complimentary bases on antisense (template) strand
p
Phosphodiester bonds formed by RNA polymerase
mRNA leaves nucleus and DNA reforms
74
Which strand contains code for the protein?
The sense strand (5' to 3') contains the code for the protein, so the antisense strand (3' to 5') is the one that binds with RNA, so the mRNA has the same sequence as the sense strand
75
describe the process of translation
mRNA binds to ribosome
complimentary tRNA anticodon binds, carrying amino acid
another tRNA molecule corresponding to the next codon binds, only two tRNAs can bind at the same time
the amino acids are joined by a peptide bond via peptidyl transferase
the ribosome moves along the mRNa chain, releasing the first tRNA
sequence is repeated until polypeptide formed
76
describe the structure of tRNA
a folded strand of RNA that is folded so that an anticodon is at one end. The anticodon binds to the complimentary mRNA codon. tRNA carries a corresponding amino acid
77
What is ATP used for?
synthesis
transport
movement
78
describe the structure of ATP
nucleic acid with adenine (base), ribose sugar and 3 phosphate groups
79
how is energy released from ATP?
phosphate group is broken off by addition of water, leaving inorganic phosphate and ADP.
80
what are the properties of ATP
small- easily moves in and out of cells
water soluble- many processes happen in aqueous conditions
releases enough energy for reactions to occur, but so much that it is lost as heat
easily regenerated with energy
81
what type of protein is an enzyme?
globular protein
82
what is the induced fit hypothesis?
The idea that the active site slightly changes shape as the substrate enters. This puts strain on the substrate, helping to lower the activation energy
83
What is an intracellular enzyme?
enzymes that act within cells. Catalase is an example
84
What is an extracellular enzyme, and why are they important in digestion?
enzymes that act outside cells. They are important because nutrients are often polymers such as proteins and polysaccharides. They must be broken down into smaller molecules to enter through the cell surface membrane
85
how is starch broken down?
Starch is broken down into maltose by maltase(disaccharide)
| Maltose is broken down into glucose by maltase
86
What enzyme breaks proteins into smaller peptides?
Trypsin
87
How does temperature affect enzyme activity?
As temperature increases, so does kinetic energy, causing more enzyme substrate complexes to form. This increases rate of reaction. However, if temperature exceeds an optimum level, the enzyme will denature, and activity will rapidly decrease as the active site will no longer be complimentary
88
what is Q10?
How much the rate of reaction increases with a 10 degree increase in temperature. It is often taken as 2 for most enzyme controlled reactions
89
how does pH affect enzyme activity?
A small variation will slightly denature the enzyme and therefore reduce activity, but if returned to normal levels, the enzyme will become renatured. A more significant variation however, will permanently denature the active site of the enzyme, and therefore reduce enzyme activity
90
How does increasing substrate concentration change enzyme activity
The rate of reaction will increase as more enzyme-substrate complexes can be formed. However, if all active sites are saturated, a new Vmax will not be formed as substrate concentration is no longer the limiting factor
91
How does increasing enzyme concentration change enzyme activity ?
The rate of reaction will increase as there is more active sites in a given area, leading to more enzyme-substrate complexes. The Vmax will also increase, as there will be more free active sites. This is until substrate concentration becomes a limiting factor
92
What is a competitive inhibitor, and how do they work?
A molecule that has a similar shape to the substrate, and so can also bind to the active site. Therefore, the enzyme cannot catalyse the reaction as enzyme-substrate complexes cannot be formed
93
how do competitive inhibitors affect rate of reaction?
The rate of reaction will decrease. However, the Vmax can still be reached when the substrate concentration far outweighs the inhibitor concentration
94
How do non-competitive inhibitors work?
The inhibitor binds to the allosteric site
This changes the tertiary structure of the enzyme, meaning the substrate cannot bind to the active site, reducing the rate of reaction. Increasing substrate concentration will increase the rate of reaction, The same Vmax will not be reached. They can be both reversible and irreversible
95
what is end product inhibition?
When the product of an enzyme controlled reaction inhibits the enzyme that produced it. It is a form of negative feedback, and is a control mechanism for the reaction, as to not make excess products and waste resources.
96
what is a cofactor?
An additional component to an enzyme that helps to catalyse a reaction. Many come for vitamins and minerals
97
What is a coenzyme?
An organic cofactor
98
What prosthetic group in the context of enzymes?
A cofactor that is a permanent feature of the enzyme.
99
What is precursor activation?
Many enzymes, such as those that can cause damage, must be controlled and only activated under certain conditions. This is done by causing a conformational change in the active site, which can be done by either:
adding a cofactor
the action of another enzyme (protease)
change in condition (temperature/pH)
100
What is compartmentalisation?
The formation of sperate membrane bound areas in a cell to allow different conditions for different reactions to happen simultaneously
101
what do channel proteins do?
provide a hydrophilic channel that allows diffusion of things like ions
102
what do carrier proteins do?
can allow both active transport and diffusion. Often involves the changing of shape.
103
what do glycoproteins do?
involved in cell signaling as a receptor for chemical signals
104
what do glycolipids do?
they are antigens that can be recognised by the immune system as either 'self' or 'non-self'
105
what does cholesterol do?
regulates fluidity
106
How does temperature effect membrane structure?
makes the membrane more fluid, and it will eventually lose structure. This increases permeability. Carrier and channel proteins can also be denatured, affecting permeability.
107
How do solvents affect membrane structure?
solvents that are less polar than water will dissolve membranes, disrupting cells. This makes the membrane more fluid and therefore more permeable.
108
What is diffusion?
the net movement of particles from a region of high concentration to a low concentration
109
what factors affect rate of simple diffusion?
temperature
| concentration gradient
110
what factors affect rate of diffusion across a membrane?
surface area
diffusion distance
temperature
concentration gradient
111
what is facilitated diffusion?
diffusion across a membrane through channel proteins. This allows polar/charged molecules to pass through. It can also involve carrier proteins. More protein channels increases the rate of facilitated diffusion
112
What is active transport?
The movement of molecules against a concentration gradient, requiring energy/ATP
113
describe the process of active transport using carrier proteins
Molecule binds to receptor on carrier protein
ATP binds to carrier protein and is hydrolysed
The energy released causes a conformational change in carrier protein
Molecule released into cell
Phosphate recombines with ADP to form ATP
carrier protein returns to its original shape
114
what are the two types of bulk transport?
Endocytosis and exocytosis
115
what are the two types of endocytosis?
Phagocytosis (solids)
| pinocytosis (liquids)
116
describe the process of exocytosis
vesicles move towards and fuse with the cell surface membrane. the contents of the vesicle are released outside the cell.
117
describe the process of endocytosis
cell surface membrane enfolds a material until the membranes eventually fuse, forming a vesicle. The vesicle moves off into the cytoplasm
118
what is water potential?
The amount of pressure exerted by water as they collide with a membrane/container
119
what is hydrostatic pressure?
pressure caused by an increase in water, and therefore volume, of a solution.
120
what happens when an animal cell is placed in a solution that is:
Hypertonic
Isotonic
Hypotonic
Water leaves cell and it shrinks (crenation)
No net osmosis, no change
Water enters cell, it swells and bursts (cytolysis)
121
what happens when a plant cell is placed in a solution that is:
Hypertonic
Isotonic
Hypotonic
Water leaves cell and membrane comes away from the cell wall (plasmolysis)
No net osmosis, no change
Water enters cell, it swells and becomes turgid, with cell membrane pushing against cell wall
122
What are the three phases of interphase?
G1
S
G2
123
what happens during G1?
protein synthesis, organelles replicate, cell size increases
124
what happens during S?
DNA replication
125
what happens during G2?
cell size increases, energy stores increased and duplicated DNA checked for errors
126
What is G0?
When a cell leaves the cell cycle, and is no longer dividing
127
What are the reasons for entering G0?
differentiation
DNA has become damaged
As you age, senescence becomes more common
128
What are the three checkpoints in the cell cycle?
G1 checkpoint
G2 checkpoint
Spindle assembly checkpoint
129
What happens during prophase?
chromatin coils and condenses to form chromosomes
nuclear envelope disappears
spindle fibres formed
130
What happens during Metaphase?
Chromosomes moved to centre of cell by spindle fibres
131
What happens during Anaphase?
Chromatids separated and pulled to opposite poles
132
What happens during Telophase?
nuclear envelope reforms
| chromosomes begin to uncoil
133
What happens in cytokinesis is animals?
Cleavage furrow forms around middle of cell membrane and pulled inwards until it fuses around the middle
134
What happens in cytokinesis in plants?
vesicles assemble in the middle of the cell and fuse with each other and the cell surface membrane, dividing the cell into two. New cell wall then forms over the membrane.
135
What happens during prophase 1?
nuclear envelope reforms
spindle formation begins
bivalents form
Crossing over!
136
what happens during metaphase 1?
Homologous chromosomes assemble along metaphase plate
| Independent Assortment of Homologous chromosomes
137
what happens during Anaphase 1?
Chromosomes pulled to opposite poles
138
What happens during Telophase 1?
nuclear membrane reforms, chromosomes uncoil, then cytokinesis occurs
139
What happens during prophase 2?
nuclear envelope breaks down and spindle formation begins
140
What happens during metaphase 2?
Line up on metaphase plate
| Independent assortment of sister chromatids
141
What happens during anaphase 2?
Chromatids pulled to opposite poles
142
What happens during Telophase 2?
Chromatin formed
nuclear envelope reforms
cytokinesis then occurs, resulting in 4 haploid daughter cells
143
How are Erythrocytes adapted for their function?
biconcave for increased SA:V
No nuclei for more space for haemoglobin
can squeeze through narrow spaces
144
How are neutrophils adapted for their function?
Multi-lobed nucleus to squeeze through small gaps
| Many lysosomes to attack pathogens
145
How are sperm cells adapted for their function?
flagellum to swim
many mitochondria to swim
acrosome at head contain digestive enzymes to break down protective layers around egg
146
How are palisade cells adapted for their function?
contain chloroplasts
rectangular so can be closely packed
thin cell walls, increase carbon dioxide diffusion
large vacuole for turgor pressure
chloroplasts can move in cytoplasm for more sunlight
147
How are root hair cells adapted for their function?
Long extension which increase surface area
148
How are guard cells adapted for their function?
Become less swollen when they lose water, so the stomata close and they lose less water
thicker on one side so cell changes shape when volume changes
149
How is Squamous epithelium adapted for its function?
One cell thick to allow rapid diffusion
| found in lining of lungs
150
How is Ciliated epithelium adapted for its function?
have cilia that move in a rhythmic manner
| goblet cells also present, that release mucus to trap any unwanted particles in the air
151
How is Cartilage adapted for its function?
contains collagen and elastin
| prevents bones rubbing and causing damage
152
How is the epidermis adapted for its function?
single layer of closely packed cells covered in waxy cuticle to reduce water loss
stomata control gaseous exchange
153
How is xylem tissue adapted to its function?
elongated dead cells strengthened with lignin for structural support
154
what are the three levels of stem cell potency?
Totipotent- can differentiate to any type of cell
Pluripotent- Can form all tissue types but not an organism
Multipotent- Can form a range of cells within a certain type of tissue
155
What stem cells are found in the bone marrow?
Haematopoetic stem cells
156
What are the sources of animal stem cells?
Embryonic stem cells- totipotent at start, pluripotent after a few days
Tissue stem cells- Found in bone marrow and umbilical cord
157
Where are plant stem cells found?
meristem tissue, found in roots and shoots (where growth happens)
158
What are the uses of stem cells?
```
Heart disease
Type 1 diabetes
Parkinson's
Alzheimer's
birth defects
spinal injuries
developmental biology
```
159
What ethical issues are there with stem cells?
Destruction of embryos (life begins at conception)
When embryo has rights
Get around this with umbilical cord stem cells but they do not divide well, and Haematopoetic cells are only multipotent
