Type of cells Flashcards
1
Q
Amino acids polymerise into
A
Proteins
2
Q
Purines and pyrimidines polymerise into
A
polynucleotides
3
Q
What are the properties of the plasma membrane?
A
- surrounds all the cells
- maintain homeostasis
- selectively permeable
- lipid bilayer
- communication with the external environment
- Aids in binding and adhering
4
Q
What does the cell theory state?
A
- cells are the fundamental units of life (Schwann)
- all organisms are composed of cells (Schleiden)
- all cells come from pre-existing cells (Virchow)
5
Q
Who was the first to describe cells and what type of cells were they?
A
Robert Hooke (cellula)
Plant cells (cork)
6
Q
Who was the first to observe a living cell under the microscope and what was it?
A
Anton Van Leeunhoek
algae Spirogyra
7
Q
what is the size of the smallest object a person can see with their naked eyes?
A
- 0.2 mm (200 micrometer)
- to distinguish the object, the person has to be as close to the object as the size of the object (o.2 mm) “resolution”
8
Q
what are the differences between light microscope and electron microscope in term of magnification and resolution?
A
- Light microscope:
magnification: 1000x
resolution: 0.2 micrometer - Electron microscope:
magnification: 1,000,000x
resolution: 0.2 nanometer
9
Q
Why is the cell size limited by the surface area to the volume ration?
A
When the volume of the cell increases the ratio of the surface to the volume decreases which means that the increase in the surface area is not proportional to the increase in volume - lesser ability to exchange with the outside environment.
10
Q
How can cells overcome the surface area to the volume ratio limitation?
A
- Flattened cells (RBCs)
- Long and thin cells (neurons)
- Cells that has many tiny projections (epithelial)
11
Q
What are the types of cells?
A
- Bacteria
- Archaea
- Eukarya
12
Q
How are the eukaryotic cells different from the prokaryotic cells?
A
Prokaryotic:
* No nucleus
* No membrane-bounded compartments (organelles)
Eukaryotic:
* membrane-enclosed nucleus
* membrane-enclosed compartments (organelles)
13
Q
what are the properties of the prokaryotic cell walls?
A
- maintain the shape of the cell
- located outside the plasma membrane
14
Q
what is the prokaryotic cell wall made of?
A
- Peptidoglycan (Sugars + amino acids) -> bacteria
- Lipopolysaccharides (lipid + polysaccharides) -> Gram-ve bacteria “covers the peptidoglycan wall”
15
Q
What is a mycoplasma?
A
- a bacterium that lacks a cell wall
- unaffected by some antibiotics that target the cell wall like penicillin
- Some of them are pathogenic to humans like “M. pneumoniae”
- they have the minimum amount of DNA required to sustain life.
16
Q
What is a capsule in prokaryotic cells?
A
- a layer of slime enclosing the cell wall.
- mostly made of polysaccharides.
- protect the bacteria from white blood cells.
- help the bacteria attaching to other cells.
- Stop the bacteria from drying out.
17
Q
What is the type of bacteria that can carry out photosynthesis?
A
cyanobacteria
18
Q
What is the part of bacteria that helps some of them to swim and what is it made of?
A
Flagella (flagellum- singular) - looks like corkscrew.
Made of protein called flagellin.
19
Q
What is a Pili?
A
- threadlike structure.
- helps the bacteria to stick to other bacteria or cells.
20
Q
What are the shapes of bacteria?
A
- Spherical shape (cocci)
- Rod shaped (bacillus)
- Spiral shaped (Spirillia)
21
Q
what is the equivalent of mitosis in bacteria?
A
Binary fission
22
Q
why don’t bacteria undergo mitosis?
A
They don’t have true cytoskeleton.
23
Q
What are inclusions in Prokaryotic cells?
A
- Found within the cytoplasm.
- Reserves of lipids, starch or glycogen.
24
Q
what are endospores and where can they be found?
A
- Structures that are highly resistant to environmental stresses.
- they usually develop in vegetative cells like the bacillus and clostridium groups of bacteria.
25
How much larger are eukaryotic cells compared to prokaryotic cells?
10x
26
What are the organelles that can be found in an animal cell?
Nucleolus
Nucleus
Rough endoplasmic reticulum
Soft endoplasmic reticulum
Ribosomes
Golgi apparatus
Mitochondria
Cytoskeleton
Centrioles
Peroxisome (lysosome)
27
What are the organelles that can be found in the plant cell?
Animal cell's organelles - centrioles +
Cell wall
Chloroplast
Vacuole
28
Where can the DNA (most of it) be found in cells?
Nucleus
29
what is the function of the nucleolus?
the assembly of ribosomes from RNA and specific proteins
30
what is the nuclear pore made of?
made of about 100 different proteins and surrounded by a complex of 8 large proteins.
31
what can pass through the nuclear pore in term of size?
* Small sized substances pass freely.
* medium sized substances can pass but takes longer.
* Large sized substances need a nuclear localised signal (a short sequence of amino acids) to pass.
32
what is the endoplasmic reticulum?
a network of interconnected membranes which branch out through the cytoplasm.
33
what is the difference between RER and SER?
RER is studded with ribosome
34
what is the function of RER?
* Segregation, transportation and modification of
newly sythesised proteins.
35
what are the functions of SER?
* chemical modification of small molecules taken into the cell (drugs).
* hydrolysis of glycogen.
* synthesis of lipids and steroids.
36
what is the difference between prokaryotic and eukaryotic ribosomes?
Prokaryotic:
* float freely in cytoplasm.
* smaller
Eukaryotic:
* can be found in cytoplasm, attach to RER and inside the mitochondria and chloroplasts.
* Larger
37
what is Golgi apparatus made of?
flattened membranous sacs called cisternae
38
what are the functions of Golgi apparatus?
* Makes further modification to proteins received from RER.
* Concentrates, packages and sorts proteins.
* Synthesizes polysaccharides for plant cell walls.
39
What are the different regions of the Golgi apparatus?
* Cis region (faces the RER)
* Trans region (faces the plasma membrane)
40
What are lysosomes and what are their functions?
* vesicles containing digestive enzymes that come from the Golgi apparatus.
* Breakdown of food and foreign materials (phagocytosis)
* digest failing cellular components (autophagy)
41
what is the function of the mitochondria?
* converts potential chemical energy in carbohydrates and fatty acids to ATP.
42
How many mitochondrial proteins that were identified in the human heart cells?
650
43
what is the only organelle that has its own genome?
Mitochondria
44
what is the benefit of the cristae?
increase the surface area for the chemical reactions.
45
why is cyanide poisonous to humans?
because it blocks the transfer of electrons to the last acceptor- oxygen.
46
where can the plastids be found?
plant cells
47
what is the name of the organelle that can carry out photosynthesis?
chloroplast
48
what are the functions of the vacuoles?
* Storage- toxins
* Structure- maintain the structure of the cell
* Reproduction- synthesis of protein for development
* Digestion- contain enzymes
49
why is the membrane design called the fluid mosaic model?
because of the distribution of the floating proteins on it.
50
what are the properties of the plasma membrane?
* bi-layered
* dynamic
* perform physiological roles
* form a boundary between intra- and extracellular environments
* regulate movement of molecules from and into the cell
51
What is the type of lipids that make of the membrane?
phospholipids - have hydrophilic part (phosphate group - head) and a hydrophobic part (fatty acid - tail).
52
what are the factors that affect the fluidity of the plasma membrane?
* cholesterol
* fatty acid composition
* temperature
53
the level of unsaturated short-chain fatty acids in the plasma membrane (decrease/increase) in low temperature.
increase
54
are the integral proteins and the phospholipids in the plasma membrane chemically associated/bonded?
No, they are free to move.
55
What are the types of proteins of the plasma membrane?
* Integral membrane proteins.
* Transmembrane proteins.
* Peripheral membrane proteins.
56
what is the type of plasma membrane protein that lack hydrophobic region?
Peripheral membrane proteins
57
what is the type of plasma membrane protein that has hydrophobic regions of amino acids and can partially or entirely penetrate?
integral membrane proteins.
58
what is the type of plasma membrane protein that shows different faces on the two sides of the membrane?
transmembrane proteins.
59
what restricts the movement of some proteins in the plasma membrane?
* Cytoskeleton
* lipid rafts (have more cholesterol)
60
What is the benefit of restricting the movement of proteins?
It allows specialisation of certain regions of the cell membrane.
61
What is the name of carbohydrate-bound lipid?
glycolipid
62
what is the name of carbohydrate-bound proteins?
glycoproteins
63
what is the function of glycoproteins?
enables cell recognition. (makes antigens and flags)
64
what are the ways in which cells arrange themselves in groups?
* cell recognition
* cell adhesion
65
What are the types of cell adhesion?
* homotypic
* heterotypic
66
what are the types of junctions that form between cells in a tissue?
* Tight junction
* Gap junctions
* Desmosomes
67
Where can the tight junctions be found?
between epithelial cells
68
What are the functions of the tight junctions?
* restrict the migration of proteins and phospholipids
* prevent substance from moving through the intercellular space.
69
what is a desmosome? what is its function?
A dense plaque that is attached to:
* cell adhesion proteins
* intermediate filaments of the cytoskeleton
Hold adjacent cells together
70
What makes a gap junction?
specialized protein channels called connexons
71
what is the name of the protein that makes up the connexon?
connexins
72
what is the difference between diffusion and facilitated diffusion?
* Diffusion is used for substances that passes through phospholipid bilayer.
* Facilitated diffusion is for substances that passes through proteins.
73
What is diffusion?
the random movement of substances from greater concentration to lower concentration until equilibrium is reached.
74
what are the factors that determines the rate of diffusion?
* temperature
* size
* charge
* concentration gradient
75
what is osmosis?
the movement of water from low solutes concentration to high solute concentration.
76
What will happen to the cell if it is put in a hypertonic solution?
Shrink, water moves out
77
What will happen to the cell of it is put in a hypotonic solution?
Explode, water moves in
78
What will happen to the cell of it is put in a isotonic solution?
nothing, water moves in and out at the same rate (equilibrium)
79
How does the gate channel protein operate?
it opens up in response to a stimulus. the inside face of the channel is polar and the outside in nonpolar.
80
what gives the specificity to the ion channel?
tight fit between the ion and the channel stem
81
how many ions per sec pass through the ion channels?
one million or more.
82
what the carrier protein is called when it is loaded?
saturated
83
Types of active transport:
* Uniport
* Symport
* Antiport
84
what is the difference between the primary and secondary active transport?
Primary: only cations move against the conc. gradient
Secondary: movement of substances using the energy of established gradient.
85
what are the different types of endocytosis?
* phagocytosis
* pinocytosis
* receptor-mediated endocytosis
86
by what process the prokaryotes divide?
fission
87
what type of chromosomes prokaryotes have?
circular chromosomes
88
what are the steps of cell fission?
* DNA replication.
* two DNA molecules attached to cell membrane.
* growth of plasma membrane between the two attachment points.
* cytokinesis
89
Eukaryotic cell divide by...
mitosis
meiosis
90
what are the properties of the nucleus?
* largest organelle in the cell (animal)
* contains most of the cell's DNA
* Replication of DNA and protein transcription in the nucleus
91
what are the substances that can cross the nuclear membrane to the nucleus through the nuclear pore?
* Proteins (DNA polymerase and lamins)
* carbohydrates
* Signaling molecules and lipids
92
what are the substances that can cross the nuclear membrane from the nucleus through the nuclear pore?
* RNA
* ribosomal proteins
93
what is the short arm of the chromosome called?
p arm
94
what is the long arm of the chromosome called?
q arm
95
how many pairs of chromosomes the human body has?
22 + XY or XX (23)
96
Are all the chromosomes of the same size?
No, some of them could have as few base pairs as 50 million. others could have as many base pairs as 250 million.
97
what is chromatin?
DNA + histones
98
what is the benefit of chromatin?
allowing the DNA to be packaged in the nucleus
99
Does the coiling of DNA require energy? (yes/no)
yes
100
what provides the energy requires for the DNA coiling?
the histones' electrostatic interactions
101
what drives the electrostatic interaction between the histones and the DNA?
histones (+)
DNA (-)
102
what are the histone family proteins?
H1, H2A, H2B, H3, H4
103
What is a nucleosome?
it is the structural and functional unit of chromatin. it consists of 9 histone proteins and 166 base pairs of DNA.
104
what phases the DNA undergo to be condensed as a chromosome?
DNA -> nucleosome -> chromatosome -> chromatin (hetero/euchromatin) -> 30-nm fiber -> 300 nm long loops -> 250 nm wide fiber -> chromosome
105
what are the two major mechanisms by which DNA is made accessible for transcription?
* enzymatic modification
* displacement by chromatin remodeling complexes
106
what are the types of cytoskeleton?
* microtubules
* microfilaments
* intermediate filaments
107
what shape does the types of cytoskeletons take?
helical polymers
108
what makes microtubules?
polymerization of tubulin monomers
109
what is the properties of microtubules?
* provide rigid intercellular structure
* track for some motor proteins
110
what type of unit is exposed in the positive end of the microtubules?
B- tubulin
111
what type of unit is exposed in the negative end of the microtubules?
a- tubulin
112
what end of the microtubule usually experience elongation?
positive end (B-tubulin)
113
what does stabilize the negative end in microtubules?
centrosome lying next to the nucleus
114
what is a centrosome?
organelle that serves as the main microtubule organising centre (MTOC)
115
what is PCM?
pericentriolar material - proteins responsible for microtubule nucleation and anchoring
116
centrioles consist of....
9-triplet microtubule
117
what is the function of colchicine?
binds to tubulin and prevent it from polymerizing and subsequently cell division.
118
how is colchicine different from taxol?
colchicine prevents polymerization of tubulin.
Taxol prevent disassembling of microtubule.
119
toward what end of the microtubule kinesin moves?
plus end
120
toward what end of the microtubule dynein moves?
minus end
121
what organelle has a receptor for kinesin?
ER
122
what organelle has a receptor for dynein?
Golgi apparatus
123
what are the functions of kinesin?
* organelle movement
* transport of RNAs and proteins
* Assembly of cilia/ flagella
* signaling pathways
* Mitotic spindle formation and chromosome movemenet
124
what is the difference between cilia and flagella?
size:
flagella longer
number:
cilia present in larger number
movement:
flagella -> wave-like
cilia -> more complex 3D movement
