Fundamental features of eukaryotic cells Flashcards
1
Q
What are the fundamental features of a eukaryotic cell that you don’t see in prokaryotic cells?
A
Membranes provide compartments for processes inside the cell
2
Q
What is the main method of reproduction in Prokaryotes?
A
Binary fission, mostly asexual
3
Q
What is the main method of reproduction in Eukaryotes?
A
Mitosis or meiosis, mostly sexual
4
Q
What function does compartmentation in the cell serve?
A
Differences in pH across the membrane inside the cell
Metabolic regulations by keeping enzymes/substrate separate
Isolate toxic substances
5
Q
What affect does SA:V ration have on a cell?
A
limits the rate of exchange
6
Q
Why are cells small?
A
Need to be able to communicate with the environment, and quick communication within the cell.
7
Q
What is a coenocyte?
A
Large cell with multiple nuclei and chloroplast.
8
Q
What are the main components of the Plasma membrane?
A
bilayer of phospholipids, with various proteins embedded
9
Q
What makes up a phospholipid?
A
hydrophilic phosphate head, glycerol molecule and hydrophobic two fatty acid tails.
10
Q
What is an amphiphatic molecule?
A
Has both hydrophilic and hydrophobic parts (polar and non polar)
11
Q
What is contained within the nucleus?
A
Most of the genes contained within a eukaryotic cell
12
Q
Describe the membrane around the nucleus
A
Is an envelope, perpetuated by pore structures which are lined by protein complexes that regulate entry and exit of materials.
13
Q
How is DNA organised in the nucleus?
A
In chromosomes, which are made of chromatin.
14
Q
How many chromosomes does a human have?
A
46
15
Q
What processes take place within the nucleus?
A
Synthesis of mRNA with the instructions provided by the DNA.
16
Q
What does the Endoplasmic Reticulum consist of?
A
network of membranes and tubules called cisternae, connected to the nuclear envelope
17
Q
What is the role of the SER?
A
varies within cell type, lots of metabolic processes, e.g.. synthesis of lipids, modification of carbs and detoxification of drugs and poisons
18
Q
What is different about the RER and SER?
A
RER has bound ribosomes
19
Q
How do proteins leave the ER?
A
In vesicles
20
Q
What is the name for vesicles in transit?
A
Transport vesicles
21
Q
What are the roles of the ER?
A
protein processing, phospholipid production and membrane production
22
Q
How is the RER a membrane making factory?
A
It grows in place by adding membrane proteins and phospholipids to its own membrane.
23
Q
What is the role of the Golgi apparatus?
A
centre of manufacturing, modification, sorting and shipping
24
Q
What is the structure of the golgi apparatus?
A
flattened membrane sacs, cisternae, all staked up.
25
What are the cis and trans ends of the Golgi apparatus?
They are the poles, vesicles carrying unprocessed molecules fuse to the cis and, and the trans face gives rise to new vesicles leaving the golgi
26
What macromolecules does the golgi process?
secretes polysaccharides
27
What is the cisternae maturation model?
movement of cis to trans face
28
How are vesicles identified by the cell?
Molecular identification tags, e.g. phosphate groups.
29
What is the cytoskeleton?
a network of fibres that organise structures and activities inside the cell
30
What is the role of the cytoskeleton?
Gives support and maintains cell shape
Involved in cell motility
Regulation og biochemical activities inside the cell
31
How doe the cytoskeleton provide support in the cell?
Stabilised by balance between pressing forces executed by its elements, provides anchorage for organelles
32
why is the cytoskeleton important in animals?
No cell wall for support
33
How is the cytoskeleton different to the animal skeleton?
More dynamic, can be quickly dismantled and reassembled.
34
How is the cytoskeleton involved in cell motility?
Interaction of the cell with motor proteins.
35
How do motor proteins promote movement of vesicles along cytoskeleton?
Attach to receptors on the and can walk them along the microtubule/filaments, pathways called monorails.
36
How to motor proteins make filaments move?
Gripping organelles with microtubules and can slide them against one another
37
Describe the structure of microtubules
Hollow roads made from globular protein tubulin. Each protein is dimer
38
What does it mean if a protein is a dimer?
made of two subunits
39
What are the two subunits in the globular protein tubular?
alpha tubulin and beta tubulin
40
What is the role of microtubules
maintain cell shape, cell motility, chromosome movement, organelle movement
41
What is the role of the centrosome?
an organelle that serves as the main microtubule organizing center of the animal cell
pulling chromatids apart in cell division
42
Where is the centrosome often located?
near the nucleus
43
How are microtubules arranged within the centromere?
There is a pair of centrioles, each composed of nine sets of microtubules arranged in a ring.
44
What happens to the centriole before division?
replicates
45
What is kinesin?
a motor proteins found in eukaryotic cells. Kinesins move along microtubule filaments, generally from the centre of a cell to the periphery
46
What is dyein?
A motor protein. Dyneins are important in sliding microtubules relative to one other during the beating of cilia and flagella
47
What are ATPases?
class of enzyme that hydrolyse ATP to ADP to drive a chemical reaction
48
Name an ATPase
dyein and kinesin
49
What are cilia and flagella?
locomotor appendages
50
How are cilia and flagella held in place on the cell?
are part of a tissue layer in the cell
51
What is the role of cilia and flagella?
move cell or to move fluid over the surface of the cell
52
What is the difference between cilia and flagella?
Flagella are larger
Cilia appear in larger numbers
Different beating patterns
53
What is a primary cilium?
non motile signal receiver for the cell
54
Describe the ultrastructure of cilia and flagella
core of microtubules sheathed in extension of plasma membrane, nine doublets of microtubules arranged in a ring.
55
What is the role of a microfilament?
Actin, maintain cell shape, contraction, cytoplasmic streaming, cell motility/division
56
What is the structure of a microfilament?
Solid rods, built from globular protein actin, a twisted chain if two subunits
57
What is the structural role of microfilaments?
To bear tension
58
What is the cortex?
`Semisolid layer of cytoplasm near cell membrane due to network of microfilaments.
59
How are microfilaments important in cell motility?
Part of contractile apparatus, Filaments arranged parallel along the length of muscle cell, with thicker myosin filaments, motor proteins on filaments cause shortening of the cell.
60
What is the role of an intermediate filament?
maintains cell shape, anchorage, formation of nuclear lamina
61
How can you distinguish an intermediate filament?
Longer than microfilament, shorter than microtubule.
62
What are intermediate filaments specialised for?
specialised for bearing tension
63
How do intermediate filaments differ in cell types?
composed of different subunits
64
What is different about intermediate filaments?
more permanent fixtures of the cell than other parts of cytoskeleton, persist even after cell death e.g.. the other layer of skin.
65
What are vacuoles?
Diverse, membrane bound, maintenance compartments
66
What are the different types of vacuoles?
Food vacuoles
Contractile vacuole
central vacuole
67
What are food vacouoles?
formed by phagocytes, digestive function, takes up food by phagocytosis
68
What are contractile vacuoles?
found in fresh water protists, pump excess water out of the cell to maintain a suitable concentration of ions and molecules in the cell
69
Where is the central vacuole found?
In mature plants
70
How does the central vacuole develop?
coalescence of smaller vacuoles that have derived from the ER
71
How does the selectivity of the vacuole membrane affect the cell?
Solution inside the vacuole differs from the composition of the cytoplasm.
72
What is the solution inside the vacuole called?
cell sap
73
What is the role of vacuoles in seeds?
Hold reserves of important organic compounds in the storage cells
74
Give examples of inorganic ions stored in vacuoles
Phosphate and Chloride
75
Why is phosphate important in plants?
component of nucleic acid structure that regulates protein synthesis, important in growth. Also plays a role in photosynthesis
76
What role does the vacuole play in metabolism?
disposal for metabolic waste and by-products that could endanger the cell if they were left to accumulate.
77
How many vacuoles be used in petals?
contain pigments to colour the cells
78
How could the vacuole be used to protect against predators?
Contain compounds that are poisons that are toxic to animals
79
How are vacuoles involved in the growth of cells?
absorb water to make the cells enlarge
80
What is the roles of mitochondria and chloroplasts?
change energy from one form to another
81
What is the role of mitochondria?
site of cellular respiration
82
What is respiration?
the metabolic process that generates ATP by extracting energy from sugars, fats and other fuels with the help of oxygen
83
What are Chloroplasts?
The site of photosynthesis
84
Where are chloroplasts found?
In plants and some algae
85
What is Photosynthesis
Conversion of solar energy to chemical energy using sunlight to drive the synthesis of organic compounds such as sugars, from co2 and water
86
How many membranes do mitochondria have?
Two
87
How many membranes do chloroplasts have?
Three
88
How are membranes off mitochondria and chloroplasts made?
By their own ribosomes, which are smaller than the cell ribosomes
89
How do mitochondria and chloroplasts program protein synthesis?
Contain a small amount of their own DNA
90
What does semi autonomous mean?
Acting independently to some degree
91
How are mitochondria and chloroplast semiautonomous?
Grow and reproduce themselves inside the cell, have their own DNA and ribosomes
92
Where are mitochondria found?
In all eukaryotic cells
93
How can you tell how active a cell is?
by how many mitochondria it has, more mitochondria in more active cells
94
How big is a mitochondria?
1-10 micrometers
95
How is the outer membrane of mitochondria structured??
smooth
96
How is the inner mitochondrial membrane structured?
Convoluted
97
What are the inholdings of the mitochondrial membrane?
Cristae
98
What is the name of the area between the two mitochondrial membranes?
Intermebrane space
99
What is inside the mitochondria?
Matrix, containing enzymes, DNA and ribosomes
100
What is the benefits of the convoluted inner mitochondria membrane?
Much larger surface area for the reactions of respiration to occur
101
What pigments do you find in Chloroplasts?
Chlorophylls and carotenoids
102
How long are chloroplasts?
2-5 micrometers
103
Where are chloroplasts found?
in the leaves and other green organs of plants
104
What is the membranous system inside of a chloroplast?
Thylakoids, flattened sacs staked into grana
105
What is the fluid inside of a chloroplast and what does it contain?
Stroma, containing the DNA and ribosomes, plus enzymes needed for photosynthesis
106
What are Lysosomes?
digestive compartments
107
What is contained within lysosomes?
Hydrolytic enzymes used ti digest macromolecules
108
What environments do lysosomal enzymes work in?
Acidic
109
Where are lysosomal enzymes made?
The ER, transferred to the Golgi for processing?
110
What is different about the membrane of a lysosome?
Specialised so it doesn't destroy itself
111
What is the role of lysosomes
intracellular digestion by phagocytosis and recycling of cell materials by autophagy
112
What is autophagy?
Organic cell materials are returned to the cytosol for reuse
113
What are protein bodies?
Proteins stored for growth and d envelopment, e.g. in seeds.
114
How does the ER control quality of proteins?
Incomplete and irregular proteins are recognised in the ER and are degraded by lysosomes
115
What are Chaperones?
Proteins that assist in the proper intracellular folding of polypeptides by keeping them separate from bad influences in the cytosol.
116
What Is the model of endosymbiosis?
suggests that mitochondria and plastids were formerly small prokaryotes that began living in larger cells
117
What is an endosymbiont?
A cell that lives within a larger host cell
118
Why would endosymbiosis of a photosynthetic prokaryote be beneficial to a heterotrophic host?
Nutrients released from the endosymbiont can be used, as well as production of oxygen for aerobically respiring host cells.
119
What evidence is there to suggest mitochondria and chloroplasts evolved from prokaryotes?
enzymes and transport systems homologous to existing prokaryotes, plus both contain a circular loop of DNA and ribosomes
