Cell Structure and Diversity Flashcards
1
Q
What are the 8 characteristics that define life?
A
- cellular organisation
- reproduction
- metabolism
- homeostasis
- heredity
- response to stimuli
- growth and development
- adaption through evolution
2
Q
What is the size range of a eukaryote cell?
A
10 - 100 μm
3
Q
1mm = ? μm
A
1000
4
Q
1μm = ? nm
A
1000
5
Q
What is the size range of a prokaryote cell?
A
less than 5μm
6
Q
About how big is the nucleus of a cell?
A
10 μm
7
Q
About how big is the mitochondrion?
A
1μm
8
Q
What is the size range of viruses?
A
10 - 100 nm
9
Q
About how big are ribosomes?
A
25 nm
10
Q
About how big are proteins?
A
1 - 10 nm
11
Q
The components of a cell are measured in
A
nanometres (1/1000000 mm)
12
Q
About how big are membranes?
A
7-8 nm
13
Q
What was Darwin’s proposed mechanism for evolution?
A
Natural selection
14
Q
What are four things that are required for natural selection?
A
- Variation within a population
- Inheritance (parents passing on traits genetically)
- Selection (some variants produce more than others)
- Time (many generations)
15
Q
Outline the purpose of a phylogenetic tree
A
- represent a hypothesis about evolutionary relationships
- these relationships are depicted as two-way branch points
- each branch point represents the common ancestor of the two evolutionary lineages diverging from it
16
Q
What are the three domains that define the origin of life?
A
Eukarya
Archaea
Bacteria
17
Q
Describe the process of endosymbiosis
A
Organelles such as chloroplasts and mitochondria that are present in Eukaryote cells derived from bacteria.
The bacteria were engulfed by the ancestors of eukaryotes and were tamed
18
Q
What are the 8 ranks of living things?
A
Domain Kingdom Phylum Class Order Family Genus Species
19
Q
The domain Archaea has what sort of cells
A
Prokaryotic cells
20
Q
The domain Bacteria has what sort of cells
A
Prokaryotic cells
21
Q
The domain Eukarya has what sort of cells
A
Eukaryotic cells
22
Q
What are the 4 kingdoms that come under the domain Eukarya
A
Animalia Kingdom
Plantae Kingdom
Fungi Kingdom
Protozoa Kingdom
23
Q
What are some examples of organisms in the Protista Kingdom?
A
Slime moulds
Algae
24
Q
Which of the domains contain a nuclear envelope?
A
Eukarya
25
Which of the domains contain membrane-bound organelles?
Eukarya
26
Which of the domains contain peptidoglycan in the cell walls?
Bacteria
27
Which of the domains have circular chromosomes?
Bacteria
| Archaea
28
Which of the domains can grow at temperatures above 100°C
Some species of Archaea
29
What are some key differences between prokaryotic and eukaryotic cells?
- Eukaryotic cells contain membrane bound organelles and prokaryotic cells do not
- the DNA is in the nucleus of eukaryotic cells but in the nucleoid (non-membrane enclosed) in prokaryotic cells
30
What are some similarities between prokaryotic and eukaryotic cells?
Both have
- plasma membrane
- cytosol
- chromosomes carrying genes in DNA
- ribosomes making proteins
31
Building blocks/monomers join together to form
macromolecules
32
Macromolecules come together to make
supramolecular assemblies
33
Supramolecular assemblies come together to make
organelles
34
Amino acids (monomers) join together to form which macromolecule?
Proteins
35
Nucleotides (monomers) join together to form which macromolecule?
DNA
| RNA
36
Simple carbohydrates (monosaccharides - monomers) join together to form which macromolecule?
Complex carbohydrates (polysaccharides)
37
Glycerol, fatty acids, hydrocarbon rings (building blocks) join together to form which macromolecule?
Lipids
38
Are lipids polymers
No
39
What are some examples of supramolecular assemblies?
membranes, ribosomes, chromatin
40
What are the four levels of carbohydrates?
```
Monosaccharides (monomers)
Disaccharides
Oligosaccharides
Polysaccharides (polymer)
```
41
What are some examples of monosaccharides?
```
Hexose monosaccharides including
- glucose
- fructose
- galactose
Pentose monosaccharides including
- ribose
- deoxyribose
```
42
What are some examples of disaccharides?
- Sucrose (Glucose + Fructose)
- Lactose (Glucose + Galactose)
- Maltose (Fructose + Galactose)
43
What are some examples of polysaccharides?
- Starch eg. amylopectin (plant carbohydrate)
- Cellulose (fibre - plant carbohydrate)
- Glycogen (animal carbohydrate)
44
Amylose is
A linear component of starch
45
What are the three functions of carbohydrates?
- structure
- recognition
- energy
46
Give an example of how a carbohydrate helps with structure
Cellulose is in the plant wall which helps maintain the structure and shape of the cell
47
Give an example of how a carbohydrate helps with energy
Plants use starch for energy storage
| Animals use glycogen for energy storage
48
Give an example of how a carbohydrate helps with recognition
carbohydrates on the cell membrane can recognise viruses and bacteria and alert the immune system
they also allow the cells to communicate with other cells
49
What are some examples of nucleic acids
DNA
| RNA
50
Nucleic acids are made up of
Nucleotides
51
What three components make up a nucleotide
Phosphate group
Sugar (deoxyribose or ribose)
Base (A,C,T/U,G)
52
What are the differences between RNA and DNA?
```
RNA:
- single stranded
- (-OH) group on the 2C of the ribose sugar
DNA
- double stranded
- (H) on the 2C of the deoxyribose sugar
```
53
Proteins are polymers of
amino acids
54
What two functional groups do every amino acid have?
- NH2
| - COOH
55
What is the function of a nucleic acid?
The storage and expression of genetic information.
| They tell the cell what to do, when to do it, how much to do and when to stop doing it
56
What are some of the functions of proteins? (8)
1. structural
2. regulatory
3. transport
4. storage
5. catalytic
6. contractile
7. protective
8. toxic
57
Give an example of a structural protein
Collagen in skin and bones
58
Give an example of a regulatory protein
insulin (a peptide hormone)
59
Give an example of a transport protein
haemoglobin carrying oxygen
| Cytochrome c carrying electrons
60
Give an example of a storage protein
albumen (egg white)
61
Give an example of a catalytic protein
```
RNA polymerase (enzymes)
hydrolytic in lysosomes
```
62
Give an example of a contractile protein
actin and myosin in muscles
63
Give an example of a protective protein
antibodies
64
Give an example of a toxic protein
diphtheria toxin
65
Lipids are not
Polymers
66
All lipids are
hydrophobic
67
Give some examples of lipids (5)
1. triaclglycerol (fats)
2. steroids
3. phospholipids
4. glycolipids
5. fat soluble vitamins
68
What are three functions of lipids?
1. Structural
2. regulatory
3. energy
69
Give an example of how a lipid helps with structure
phospholipids which make up the plasma membrane and cholesterol which makes sure everything in the membrane is the right consistency
70
Give an example of how a lipid helps with regulation
Cholesterol is a regulatory lipid regulating testosterone and oestrogen
71
Give an example of how a lipid helps with energy
Fats:
| Glycerol backbone and 3 fatty acid chains
72
What must a cell do? (5)
```
Manufacture cellular materials
Obtain raw materials
remove waste
Generate required energy
Control all of the above
```
73
What are 5 purposes of organelles?
- provide special conditions for specific processes
- keep incompatible processes apart
- allow specific substances to be concentrated
- form concentration gradients
- package substances for transport or export
74
What are some organelles that both animal and plant cells have?
- Endoplasmic reticulum
- Nucleus
- Mitochondrion
- Golgi
75
What are some organelles that are only in animal cells?
- lysosomes
76
What are some organelles that are only in plant cells?
- central vacuole
| - chloroplast
77
Which cells (plants, animals, protists) have a cell wall?
Plants: present
Animals: absent
Protists: may or may not be present
78
Which cells (plants, animals, protists) have a cytosol?
Plants: present
Animals: present
Protists: present
79
Which cells (plants, animals, protists) have a plasma membrane?
Plants: present
Animals: present
Protists: present
80
Which cells (plants, animals, protists) have a central vacuole?
Plants: present
Animals: absent
Protists: present
81
Which cells (plants, animals, protists) have a nucleus?
Plants: present
Animals: present
Protists: present
82
Which cells (plants, animals, protists) have a chloroplast?
Plants: present
Animals: absent
Protists: may or may not be present
83
Which cells (plants, animals, protists) have a lysosome?
Plants: absent
Animals: present
Protists: may or may not be present
84
Which cells (plants, animals, protists) have motility?
Plants: absent
Animals: present in some cells
Protists: may or may not be present
85
What are the sizes of plant cells, animal cells and protists?
Plants: 10 - 100 μm
Animals: 10 - 30 μm
Protists: less than 1 μm to metres
86
Which cells (plants, animals) have a centrosome?
Plants: absent
Animals: present
87
Which cells (plants, animals) have flagella?
Plants: absent
Animals: present in some cells
88
Which cells (plants, animals) have a mitochondria?
Plants: present
Animals: present
89
Which cells (plants, animals) have plasmodesmata?
Plants: present
Animals: absent
90
About the plasma membrane including its function
the phospholipid bilayer which encloses the cell
Function:
controls the movement of substances into and out of the cell
91
What are some organelles that have their own membrane
- endoplasmic reticulum
- lysosomes
- mitochondria (two membranes)
- nucleus (nuclear envelope)
- chloroplast (two membranes)
92
Describe the phospholipid bilayer
made of phospholipids with a hydrophilic head and a hydrophobic tail
the hydrophilic heads shield the hydrophobic tails from the aqueous environment inside and outside of the cell
93
What is passive transport?
Transport of molecules across the plasma membrane which requires no energy
94
What are some examples of passive transport?
- diffusion
| - facilitated diffusion (including osmosis)
95
Explain the process of diffusion
lipid soluble (hydrophobic) molecules such as steroid hormones and gases move down their concentration gradient into the cell without the use of energy
96
Explain the process of facilitated diffusion
the movement of hydrophobic molecules such as glucose, ions and water down their concentration gradient into the cell through channels and carriers without the use of energy
97
Explain the process of osmosis
the movement of water from a low solute concentration to a high solute concentration through channels called aquaporins without the use of energy
98
Why is osmosis an example of facilitated diffusion
Because it is the movement of hydrophilic water across the hydrophobic membrane and therefore requires channels
99
What is active transport?
Movement of molecules across a membrane with the use of energy
100
What is required for active transport?
Transport proteins that require energy supplied by ATP
101
What is the purpose of active transport?
To move substances against their concentration gradient which allows the cell to have a different concentration of a substance that is different to its surroundings
102
What is co-transport?
an example of indirect active transport
103
Describe the process of co-transport:
```
once substance (often H+) is pumped across the membrane via active transport (using energy)
the concentration gradient of H+ ions are used to drive a second substance (eg. sucrose) against its concentration gradient (no energy required)
```
104
What are 4 roles of membrane proteins
1. signal transduction
2. cell recognition
3. intercellular joining
4. linking the cytoskeleton to the extracellular matrix
105
What is signal transduction?
relaying messages from environment to the inside of the cell
106
What sort of messages would the environment send into the cell through signal transduction?
```
grow
divide
move
make something
die
```
107
What is the significance of cell recognition?
the proteins allow the cells to interact close up
| this involves glycoproteins
108
What are glycoproteins?
Proteins with added sugars
109
What is intercellular joining?
Proteins forming long lasting connections between the cells
110
What is the significance of linking the cytoskeleton to the extracellular matrix?
It allows the cell to physically connect with protein structures outside the cell
111
What is the function of the nucleus?
Contains chromosomes and controls protein expression
112
What is the function of the rough endoplasmic reticulum?
- ribosomes attached to the rough ER synthesise secretory (eg. glycoproteins) and membrane-bound proteins
- rER produces the protein and enzymes in the lumen add carbohydrates
- secretory proteins leave rER in vesicles and go to the golgi
113
What is the function of the lysosome?
Fuse with incoming food vacuoles or unwanted/damaged organelles and break down/digest them
114
What does the endomembrane system include?
| 7-8
- nuclear envelope
- endoplasmic reticulum (both smooth and rough)
- Golgi
- vesicles
- lysosomes
- vacuoles
- plasma membrane
115
What are the functions of the smooth ER? (4)
1. metabolism (breaking down and putting together) of carbohydrates
2. lipid synthesis for membranes
3. detoxification of drugs and poisons
4. storage of Ca2+ ions
116
Can the amount of smooth ER be increased or decreased to meet demand?
Yes
117
Proteins in vesicles leave the _______ in _________ and enter the ________ face of the __________
rough ER
vesicles
cis
golgi
118
Describe the golgi including basic function
- a series of membrane sacs and associated vesicles
- has a cis and trans face of different polarities
- receives, modifies, sorts and ships proteins arriving from the ER
119
Vesicles from the ER arrive at the golgi at the _______ face
cis
120
Processed vesicles leave the golgi at the _______ face
trans
121
What are three functions of the golgi
- glycosylation
- sorting proteins
- directing vesicle traffic
122
Describe glycosylation
- addition (or modification) of carbohydrates to proteins
| - golgi also produces polysaccharides which may be excreted from the cell
123
Describe the process of sorting proteins at the golgi
adding molecular markers to direct proteins to the correct vesicles before 'budding' from the trans face
124
Describe the process of directing vesicle trafficking by the golgi
- adds molecular tags to the vesicles to direct them to the correct target
- these molecular tags act as docking sites when they reach their target
125
What are the two methods of bulk transport across the plasma membrane?
Exocytosis
| Endocytosis
126
Describe exocytosis
transports materials (glycoproteins) out of the cell or to the cell surface
127
What are two types of exocytosis?
Constitutive exocytosis
| Regulated exocytosis
128
Describe constitutive exocytosis
the unregulated release of extracellular matrix proteins
129
Describe regulated exocytosis
the controlled release of hormones and neurotransmitters
130
Describe endocytosis
The cell takes in molecules and particulate matter at the plasma membrane
131
What are three types of endocytosis
Pinocytosis
| Phagocytosis and Receptor-mediated endocytosis
132
Describe pinocytosis
the non-selective uptake of cellular fluid containing various solutes such as proteins and sugars
the uptake vesicle is formed with the aid of a coat protein
133
Describe phagocytosis
uptake of "food" particles into a vesicle with a phagocytic vacuole which is digested by lysosomes
134
Describe receptor-mediated endocytosis
- specialised/picky form of pinocytosis
- allows the cell to take up bulk quantities of specific substances which may be present at only low concentrations in the extracellular fluid
- receptor proteins selectively capture the required solute
135
What do lysosomes contain
hydrolytic enzymes
136
What sort of things does the lysosome break down (4) and where do they go?
proteins, lipids, carbohydrates and nucleic acids and then they are released into the cell
137
The process of lysosomes breaking down unwanted cellular material is called
autophagy
138
How are vacuoles important in plants?
- they can perform lysosome-like functions
| - the large central vacuole absorbs water allowing plants to grow without a large increase to the cytoplasm
139
What is the cytoskeleton?
essentially the stuff that the organelles are floating in
140
Describe the cytoskeleton including its function
- helps maintain cell shape
- helps position organelles within a cell
- can rapidly assemble and disassemble
- highly dynamic but provides stability
141
What are the three main components of the cytoskeleton?
- microtubules
- microfilaments
- intermediate filaments
142
What are microtubules made of?
tubulin subunits
143
Which of the components of the cytoskeleton can radiate out from an organising centre (centrosome)
microtubules
144
Microtubules resist
compression
145
Functions of microtubules
- help maintain cell shape
- can also help with motility
- involved in vesicle/organelle motility
146
Tubulin subunits are
proteins
147
Give an example of how microtubules can help with motility
flagella
| cilia
148
Explain how microtubules help with vesicle/organelle motility
- An ATP-powered motor protein attaches to the microtubule
- this protein is also bound to a vesicle or organelle
- when given ATP, the protein changes shape and 'walks' down the microtubule allowing movement of vesicles and organelles within a cell
149
What are microfilaments made of?
actin subunits
150
Microfilaments form
- linear strands
| - 3D networks (using branching proteins)
151
Microfilaments resist
tension
152
Functions of microfilaments
- maintain cell shape
can also help with
- cell movement
153
Explain how microfilaments can help resist tension and maintain cell shape
There is lots of tension around the edges of the cell but the 3D cortical network under the plasma membrane holds it together, helps make this region less fluid and helps maintain cell shape
154
Explain how microfilaments can help with cell movement
```
Interactions between actin and myosin
This allows:
- muscle contraction
- amoeboid movement
- cytoplasmic streaming
```
155
What are intermediate filaments made from?
various proteins such as
- keratins (hair)
- lamins (nucleus)
- neurofilaments (neurons)
156
Which of the components of the cytoskeleton form relatively permanent structures?
intermediate filaments
157
What are the functions of the intermediate filaments?
- maintain cell shape
| - anchor organelles
158
How are cells joined together?
cell junctions
| extracellular matrix
159
What are the three types of cell junctions?
- tight junctions
- gap junctions
- desmosomes
160
Describe tight junctions
- hold neighbouring cells tightly together
- cells 'sewn' together
- prevents movement of fluid across cell layers
161
Tight junctions prevent the movement of _______ across cell layers
fluid
162
Describe desmosomes
- anchoring junction
- provides attachment between sheets
- heavy duty
- connected into the cell by intermediate filaments
163
Desmosomes are connected into the cell by
intermediate filaments
164
Describe gap junctions
- a point of cytoplasmic contact between the two cells
- allows ions and small molecules to pass from cell to cell
- allows rapid intercellular communication
165
What is the ECM composed of
- material secretes by the cells
| - most ECM proteins are glycoproteins
166
What are glycoproteins?
proteins with added carbohydrates
| big protein, little carbohydrate
167
What is the most abundant ECM glycoprotein?
collagen
168
What are collagen fibres embedded in?
proteoglycan complex matrix
169
How do endocytosis and exocytosis relate to the addition and/or removal of materials from the plasma membrane?
Endocytosis:
Plasma membrane folds inwards, slowly ingesting substances or particles.
The membrane eventually buds off within the cytoplasm and brings items into the cell’s interior.
Exocytosis:
Secretory vesicles fuse with the plasma membrane, discharging the contents of the vesicle to the exterior of the cell.
170
What is the approximate diameter of the microtubules?
25 nm
171
What is the approximate diameter of the microfilaments?
7 nm
172
What is the approximate size of the intermediate filaments?
8-12 nm
173
What are proteoglycans?
Proteins with extensive sugar additions
| little protein, big sugar
174
What is the role of the proteoglycans in the ECM?
to trap water to help resist compression and therefore retain tissue shape
175
Collagen in the most abundant glycoprotein. Name another glycoprotein
Fibronectins
176
What is the purpose of fibronectins?
To attach the cells to the ECM
177
What are integrins?
Membrane proteins
178
What is the purpose of integrins?
To connect the ECM to the cytoskeleton
179
Explain how integrins and fibronectins work together and describe their combined function
The integrin spans the plasma membrane which connect the cytoskeleton (inside) to the ECM (outside).
Fibronectins attach to the integrin (outside) which provides link between the cells and the ECM.
The two provide a communication link from ECM to the cell interior
180
What makes up a plant cell?
The cell wall and the protoplast
181
What is the protoplast?
The plasma membrane and everything inside it
182
What is the cell wall made of?
- cellulose
- pectin
- hemicellulose
- extensin
183
What is in the 1st phase of the (primary) cell wall?
- cellulose
184
What is in the 2nd phase of the (primary) cell wall?
- pectin
- hemicellulose
- extensin
185
What does cellulose form in the cell wall?
microfibrils
186
What are the function(s) of pectin?
it binds water and has gel like properties
187
What are the function(s) of hemicellulose?
helps form a rigid structure
188
What are the function(s) of extensin?
Cross links between pectin and cellulose to dehydrate the cell wall which means it can become more rigid
(also allows it to grow)
189
How is the primary cell wall synthesised?
- cellulose microfibrils synthesised at the plasma membrane
- pectin and hemicellulose come from the golgi and are transported to the plasma membrane in vesicles via exocytosis
- extensin comes from the rough ER and is transported to the plasma membrane in vesicles via exocytosis
190
What is the non-crystalline matrix?
Phase 2 (pectin, hemicellulose, extensin)
191
Pectin and hemicellulose are examples of
polysaccharides
192
Exensin is an example of
a cell wall protein
193
What sort of exocytosis releases the extracellular matrix proteins in animals but pectin, extensin and hemicellulose in plants?
constitutive exocytosis
194
What are the functions of the cell wall?
- cell shape
- structural support (protoplast pushing against the cell wall)
- prevents excessive water uptake
195
Describe how the cell wall helps with structural support
The protoplast pushes against the cell wall
- in young cells, this helps it grow
- in mature cells, the extensin cross linking helps keep the cell rigid and stops it from bursting
- loss of water causes wilting
196
Describe how the cell wall prevents excessive water uptake
The water enters the cell by osmosis (into the central vacuole) and the protoplast expands and pushes against the cell wall.
Pressure from the cell wall limits the volume of water that can be taken up.
197
How are vacuoles important in the prevention of excessive water uptake?
they contain water and make up such a large portion of the protoplast
198
What is a vacuole?
- an organelle surrounded by a single membrane
| - it is highly selective and controlling
199
What is osmosis?
The movement of water across a selectively permeable membrane from where there is a low solute concentration to where there is a high solute concentration
200
In a hypotonic solution, an animal cell can become
lysed
201
In a hypertonic solution, an animal cell can become
shrivelled
202
In an isotonic solution, a plant cell can become
flaccid
203
In a hypertonic solution, a plant cell can become
plasmolysed
204
Not all plants have a
secondary cell wall
205
When is the secondary cell wall produced?
once the cell is grown
206
How many layers does the secondary cell wall have?
3
207
What are the chemical characteristics of the secondary cell wall?
More cellulose
Less pectin
lignin
208
What is lignin?
A complex polymer that confers strength and rigidity to the secondary cell wall and acts to exclude H2O
209
What is the function of the secondary cell wall?
It provides structural support for specific cell types such as water transferring cells, and for the whole plant
210
How do plant cells communicate?
Via the plasmodesmata
211
What are plasmodesmata?
Intercellular connections that allow cell to cell communication by allowing free exchange of small molecules
212
How do plants get their energy?
Through the process of photosynthesis
213
Why do cells need energy?
- mechanical work
- to make new materials
- for transport
- to maintain order
214
Why would cells need to do mechanical work?
To move proteins and vesicles
215
Why would cells need to make new materials?
for growth and replacement
216
What would cells need to transport?
molecules across the membrane
217
Where does respiration take place?
in the mitochondria
218
Describe the mitochondria
- 1-10 μm
- 1-1000 per cell
- contains mitochondrial DNA and ribosomes
219
How many membranes does the mitochondria have?
2
220
Where is the mitochondrial matrix?
inside the inner membrane of the mitochondria
221
What are the cristae?
the highly folded inner membrane of the mitochondria
222
What is the inter membrane space?
The space in between the two membranes of the mitochondria
223
What is the purpose of cellular respiration?
to harvest chemical energy from glucose
224
What are the three stages of respiration?
1. glycolysis
2. pyruvate oxidation and citric acid cycle
3. oxidative phosphorylation
225
Where does glycolysis occur?
in the cytosol
226
What is broken down in glycolysis?
| What is formed?
- Glucose is converted to two lots of a 3C molecule called pyruvate
- it also generates 2ATP
- electrons are transferred to the high energy electron carrier (NAD+) making NADH
227
Where does pyruvate oxidation and citric acid cycle take place?
In the mitochondrial matrix
228
Describe pyruvate oxidation and the citric acid cycle
- pyruvate is converted to acetyl CoA
- acetyl CoA enters the citric acid cycle
- output is ATP and high energy electron carriers NADH and FADH2
229
Oxidative phosphorylation consists of what two stages?
The electron transport chain
| Chemiosmosis
230
Describe the electron transport chain
- electron carriers NADH and FADH2 shuttle high energy electrons to the inner mitochondrial membrane
- the e- move through protein complexes embedded in the inner membrane
- as the e- move, H+ are pumped across the membrane from the mitochondrial matrix into the intermembrane space
- H+ accumulate in the intermembrane space, creating a concentration gradient
- this initiates chemiosmosis
231
Where does oxidative phosphorylation take place?
The cristae
232
Describe the process of chemiosmosis
- H+ goes through ATP synthase (embedded in the inner mitochondrial membrane) from the intermembrane space into the mitochondrial matrix
- this allows ATP synthase to convert ADP to ATP
233
What is an advantage of using ATP for energy?
it enables the controlled release of energy
234
Where does photosynthesis take place?
The chloroplasts
235
Describe the structure of the chloroplast
- outer membrane
- intermembrane space
- inner membrane
- stroma
- granum
- thylakoid
- thylakoid space
236
A stack of thylakoids is called a
granum
237
Inside each thylakoid is the
thylakoid space
238
Inside the inner membrane where the DNA, ribosomes and thylakoids are, is called the
stroma
239
Photosynthesis consists of what two processes?
light reactions
| Calvin cycle
240
What is the purpose of the light reactions?
capturing light energy to convert it into chemical energy
241
Describe the light reactions
- light energy is absorbed in by chlorophyll (contained in photosystems inside the thylakoid membrane)
- this excites electrons
242
The nucleus is surrounded by the
nuclear envelope
243
The nuclear envelope consists of how many membranes?
2
244
What is the purpose of the nuclear pore complex
It controls the movement of molecules in or out of the nucleus
245
What needs to leave the nucleus?
mRNA
tRNA
ribosomal subunits
246
What needs to enter the nucleus?
control signals (like when to turn a gene on or off)
building materials
energy for chemical synthesis
247
What is the inner surface of the nucleus lined with?
the nuclear laminar
248
Describe the nuclear laminar
It is the inner surface of the nucleus which is composed of intermediate filaments.
It helps maintain the shape of the nucleus and to organise the packing of the DNA within the nucleus
249
What is the nucleolus?
A prominent nuclear structure within non-dividing cells and it is responsible for making rRNA (combines with proteins to produce ribosomes)
250
The DNA helix twists around proteins called
histones (H2 and H4)
251
The DNA helix twists around proteins called histones (H2 and H4) which forms a strand of "beads". Each bead is called a
nucleosome
252
The DNA helix twists around proteins called histones (H2 and H4) which forms a strand of nucleosomes. The DNA continues to wrap around which histones?
H1
253
What is euchromatin?
less dense DNA
| it contains genes being used by that cell
254
What is heterochromatin?
more dense DNA
| contains genes not being used by that cell
255
Where does carbon fixation/Calvin cycle take place?
In the stroma
256
Where do the light reactions take place?
In the thylakoid membranes
257
Describe the light reactions
- in a continuous loops, water is split into O2 and H+ to give e-
- the e- are in chlorophyll in photosystem || where light energy absorbed by the chlorophyll excites them
- the e- move through the cytochrome complex which allows H+ to move from the stroma across the thylakoid membrane into the thylakoid space
- the e- move through photosystem | and then into a complex to convert NADP+ and H+ into the e- carrier NADPH
- the H+ in the thylakoid space go through ATP synthase back to the stroma to generate ATP
258
What are photosystems?
protein complexes that contain chlorophyll
259
What is the equation for photosynthesis?
6CO2 + 6H2O -> C6H12O6 + 602
260
What is the equation for respiration?
C6H12O6 + 602 -> 6CO2 + 6H2O + energy
261
What are the inputs of photosynthesis?
light
H2O
CO2
262
What is produced during the light reactions of photosynthesis and what are these used for?
ATP and NADPH to be used in the Calvin Cycle
263
What are the outputs of photosynthesis?
O2 and C6H12O6
264
What are the three stages of the Calvin Cycle?
Fixation
reduction
regeneration
265
Describe carbon fixation stage of the Calvin Cycle
one at a time, three CO2 molecules bind to RUBP to form a total of three unstable 6C chains. These break into six 3C chains
this uses ATP (total 6ATP -> 6ADP)
266
Describe reduction stage of the Calvin Cycle
Each 3C molecule is converted into another 3C molecule called G3P
six NADPH are each converted into NADP+
267
Describe regeneration stage of the Calvin Cycle
the other five G3P will be converted back into three RUBP molecules to restart the cycle
this uses ATP (total 3ATP -> 3ADP)
268
What enters the Calvin cycle?
3 x CO2
9 x ATP
6 x NADPH
269
What exits the Calvin cycle?
1 x G3P (every three turns)
3 x ADP
6 x NADPH
270
How did chloroplasts and mitochondria originate?
An ancestral prokaryote engulfed an aerobic bacteria and tamed them and they became the mitochondria and the chloroplasts
271
Name two regulatory lipids derived from cholesterol
Testosterone and Oestrogen
