Cells Flashcards
(84 cards)
1
Q
Who was the first one to create a microscope and when?
A
Anton van Leeuwenhoek in the 1600s
2
Q
What size are plant and animal cells?
A
Approximately 10-100 micrometers
3
Q
What size are the most bacteria?
A
Approximately 1-10 micrometers
4
Q
What is the size of chloroplast?
A
Approximately 1 micrometer
5
Q
What size are viruses?
A
20-300 nano meters
6
Q
What size are proteins?
A
5-10 nano meters
7
Q
What size are amino acids?
A
Approximately 1 nano meter
8
Q
What size are atoms?
A
0.1 nano meters
9
Q
What are the 2 groups of living things?
A
Non cellular: viruses
Cellular: prokaryotes and eukaryotes
10
Q
What are examples of prokaryotes and eukaryotes?
A
Prokaryotes: bacterial cells
Eukaryotes: fungal cells, protoctistan, animal cells, plant cells
11
Q
What are 6 main things we know about viruses?
A
1) non cellular
2) size range 20-300nm
3) don’t contain cytoplasm or organelles
4) covered in a protein coat
5) no chromosomes, just RNA or DNA
6) depend on cells for metabolism and reproduction
12
Q
What do we know about bacterial cells?
A
1) single celled
2) lack distinct membrane bound nucleus
3) DNA usually a single, naked chromosome
4) have cell walls and many secrete capsule
13
Q
What do we know about protoctistan cells?
A
1) mainly single cells or exist as cell colonies
2) posses nucleus and membrane bound organelles
3) some are autotrophic
4) some are heterotrophic
14
Q
What do we know about fungal cells?
A
1) possess a nucleus and membrane bound organelles
2) plant like but lack chlorophyll (have a cell wall)
3) rigid cell walls contain chitin
4) heterotrophic
15
Q
What are the structures that are present in prokaryotes?
A
1) cell wall
2) plasma membrane
3) cytoplasm
4) pili
5) flagella
6) ribosomes
7) naked DNA (nucleoid)
8) mesosome
16
Q
What are the structures that are SOMETIMES present in prokaryotes?
A
1) plasmids
2) slime capsule
3) photosynthetic membranes
17
Q
Why do prokaryotes have cell walls?
A
Prevents damage from outside and bursting from internal pressure
18
Q
Why do prokaryotes have plasma membrane?
A
To control the transfer of substances
19
Q
Why do prokaryotes have cytoplasm?
A
Contains enzymes that catalyse the chemical reactions of metabolism
Location of growth, metabolism, and replication.
(Also known as proto-plasm. Gel-like matrix of water, enzymes, nutrients, wastes and gases and contains cell structures)
20
Q
Why do prokaryotes have pili?
A
For adhesion.
Some bacteria can produce conjugation or sex pili that enables conjugation.
21
Q
Why do prokaryotes have flagella?
A
For locomotion
22
Q
Why do prokaryotes have ribosomes?
A
For protein synthesis
Found in the cytoplasm or bound to membrane
Made of protein and rRNA
Composed of 2 subunits
23
Q
Why do prokaryotes have nucleoid?
A
For storing genetic information.
Region of cytoplasm where prokaryote’s genome DNA is located.
Usually single and circular
24
Q
Why do prokaryotes have mesosome?
A
Plays role in cellular respiration and movement of DNA
Is in folding of the plasma membrane
25
Why do prokaryotes sometimes have plasmids?
For extra genetic material (5-100 genes)
Can provide genetic information to promote: antibiotic resistance, conjugation.
Can be passed from one cell to another
Used as vectors in genetic engineering
26
Why do prokaryotes sometimes have slime capsule?
Protects the cell against chemicals and dying out
27
Why do prokaryotes sometimes have photosynthetic membranes?
Possess pigments to assist in photosynthesis
28
What metabolic activities do prokaryotes perform?
Photosynthesis (blue-green bacteria)
Nitrogen fixation (in nitrogen fixation)
Fermentation (absorb large organic substances and convert them into other organic substances) (heterotrophic) example: yoghurt
29
Why do bacteria have granules?
It’s a way of storing nutrients.
Staining some granules aids in identification.
30
Do prokaryotes have a cytoskeleton?
Yes, it is a cellular skeleton in the cytoplasm.
Up until recently thought to be a future of eukaryotic cells.
31
What are relations between bacteria and water?
Cell walls prevent them from exploding in hypotonic solutions but most bacteria are not ok in hypertonic environments (can be plasmolyzed).
The water moves out of the bacterium and it dies of “HYPEROSMOTIC SHOCK” (desiccation)
32
What is a gram positive bacteria?
Have cell walls mainly composed of peptidoglycan or murein.
33
What is gram negative bacteria?
Have cell walls composed only of a thin layer of peptidoglycan and an outer membrane with a lipopolysaccharide (phospholipid).
34
What is a peptidoglycan?
A huge polymer of interlocking chains of alternating monomers.
Provides rigid support and at the same time is permeable.
35
What is the composition of peptidoglycan?
Backbone is composed of 2 amino sugar derivatives of glucose. The “glycan” part of of peptidoglycan: NAG (N-acetylglucosamine) and NAM (N-acetlymuramic)
NAG and NAM strands are connected by interlocking peptide bridges. The “peptide” part of peptidoglycan.
36
What do we call a bacterial plasma membrane and cell wall?
Together they are called the cell envelope (busta cellulare)
37
What is glycocalyx?
It’s an external layer outside the cell wall of some bacteria
38
In what forms glycocalyx exists?
Slime layer: glycoproteins loosely associated with the cell wall. Causes bacteria to adhere to solid surfaces and prevents the cell from drying out.
Capsule: polysaccharides firmly attached to the cell wall. Adhere to solid surfaces and to nutrients. Also protects bacteria from being phagocytized by cells of the hosts immune system.
39
What are endospores?
These are dormant, tough, and non-reproductive structures produced by sine bacteria.
40
What are the bacterial shapes?
1) bacillus
2) coccus
3) spiral shaped: spirillum- spiral with rigid cell wall, flagella
spirochete: spiral with flexible cell wall, axial filament
41
What are the arrangements of bacilli?
Diplobacilli
Streptobacilli
42
What are arrangements of cocci?
Coccus
Diplococci
Staphylococci (clusters)
Streptococci (chains)
Sarcina (in packages)
43
What are the 2 structures in prokaryotes used for movement?
1) flagella: long, rope-like external structure
| 2) axial filaments: internal structures trapped within the periplasm
44
What is the part inside the nucleus and what is it called?
Nucleolus holds nucleic acids and proteins.
45
Why do we have proteins in the cell membrane?
They help with communication with the surrounding environment.
They receive and send chemical signals from other eukaryotic cells.
They interact with prokaryotic cells during the infection.
46
What is the site of ribosome synthesis?
Nucleolus
47
What do ribosomes do?
They are the site of protein assembly
48
What is the difference between prokaryotic and eukaryotic ribosomes?
Eukaryotic ribosomes are larger, and contain twice the amount of ribosomal RNA.
(Ribosomes are small cellular machines made of proteins and ribosomal RNA)
49
What is the endoplasmic reticulum made of?
Made up of membranous tubules and cisternae (sacs)
50
What does smooth ER do?
1) synthesis and transport of lipids
2) controls glucose glycogen conversion in liver and muscles
3) detoxification of drugs and other poisons
4) SACROPLASMIC RETICULUM (muscle ER) stores calcium needed in muscle contraction
51
What does rough ER do?
1) synthesis and transport of proteins
52
What does Golgi apparatus do?
It’s a packaging organelle (like ER)
Products of the ER are modified and stored here. (Modifies and packages proteins)
It takes simple molecules and combines them to make molecules that are more complex. It then takes those big molecules, packages them in vesicles and either stores them for later use or sends them out of the cell.
It also builds LYSOSOMES.
53
Why do we have lysosomes?
These contain enzymes that were created by the cell, and then, they digest things or break down the cell when it dies.
Usually found only in animal cells.
Have enzymes that work in oxygen-poor areas and lower pH.
54
What is apoptosis?
Programmed cell death.
55
What type of vacuoles there are?
Food vacuole (storage)
Contractile vacuoles (pump extra water out of the cells in freshwater protists)
Central vacuole (in plant cells, stores organic compounds, inorganic ions K+ Cl-, and water. Surrounded by TONOPLAST)
56
What are peroxisomes?
These contain enzymes that transfer hydrogen from various substances to oxygen, producing H2O2 as a byproduct.
These hold on to enzymes that require oxygen (oxidative enzymes).
Functions:
1) break fatty acids down into smaller molecules for cellular respiration.
2) detoxify alcohol in liver.
57
Describe cytoskeleton.
1) maintains shape of the cell
2) responsible for movement of cell and movement of organelles within cell.
3) made of 3 types of protein fibres:
Microtubules (25 nm diameter)
Microfilaments (7nm diameter)
Intermediate filaments (8-12 nm diameter)
58
What are the functions of microtubules?
Hollow tubules
Made up of A and B tubulin
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Responsible for:
1 cell motility (cilia/ flagella)
2 chromosome movements (mitosis- centrioles)
3 movement of organelles
4 maintenance of cell shape
```
59
What are the functions of intermediate filaments?
Made up of fibrous proteins. Made up of keratin.
Responsible for:
1 structural support
2 maintenance of cell shape
3 anchors nucleus and certain organelles
60
What are the functions of micro filaments?
Made up of 2 intertwined strands of actin.
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Responsible for:
1 muscle contraction
2 cytoplasmic streaming
3 cell motility (pseudopodia)
4 cell division
5 maintenance of/ changes in cell shape
```
61
Why do we have centrioles?
Only found in animal cells.
May give rise to cilia and flagella.
May be involved in formation of spindle fibres in animal cells, but not plants (help in division of cells).
Visible only during cell division.
Microtubule triplet arranged in 9+0 manner.
62
What do we know about flagella and cilia?
Structures for cell motility
Flagella is long and few in numbers
Cilia is short and numerous
Internal structure 9+2
Basal body structure 9+0 like centrioles but has microtubule couple.
Has an additional “structure” called DYNEIN
63
What are different types of cell walls?
Primary cell wall thin; cellulose
Secondary cell wall thicker; pubs in woody plants
64
What do we know about extracellular matrix?
Found in animal cells
Made up of glycoproteins (collagen) and proteoglycans (proteins + carbohydrates)
Provides support and Anchorage for cells
Differs from one cell type to another.
65
How are neighbouring plant cells connected?
Through plasmodesmata
66
How are animal cells connected?
1 tight junctions: membrane proteins interlock
2 desmosomes ( anchoring junction): intermediate filaments “sew” membranes together
3 gap junctions: channels align allowing materials to flow between cells
67
What do plant cells have what animal cells don’t?
Cell wall
Chloroplasts
Chlorophyll
Plastids: organelles that store things such as food in the plant cell
68
What is the structure of lipid bilayer?
75% phospholipids
20% cholesterol
5% glycolipids
69
What are the functions of membrane proteins?
Ion channels
Carriers: selectively move polar substances
Receptors: specific to various molecules (ligand- substance that binds to receptor)
Linkers: help anchor cells together by binding proteins or filaments together
Cell identity markers: mainly glycoproteins and glycolipids (recognise other similar cells in tissue formation/ recognise foreign cells ex. ABO blood types)
70
Describe membrane permeability to different substances.
Permeable: oxygen, carbon dioxide, steroids
Non-permeable: ions, large polar molecules
Slightly permeable: small uncharged polar molecules like water and urea
71
Examples of passive transport
Simple diffusion
Facilitated diffusion
Filtration
Osmosis
Dialysis
72
Examples of active transport
Primary active transport
Secondary active transport (co-transport): uses energy stored in Na+ and H+ gradient used to drive another substance across membrane
Endocytosis: pinocytosis- non specific fluid (all cells)/ phagocytosis- solid materials (specialised cells)/ receptor mediated- specific materials (requires energy, calcium and micro filaments)
Exocytosis
73
What protein channels there are?
Leaky channels
Gated channels: 1) voltage gated 2) ligand gated
74
Diffusion can take place through...
Lipid bilayer
Lipid soluble substances: oxygen, carbon dioxide, steroids, alcohol etc.
Lipid insoluble: water (through spaces between lipid molecules) urea (less or no permeability)
Electrolytes: impermeable sugar, charge on fatty acid chain
75
Facilitated diffusion
Use of protein channels (ion channels) for too polar or highly charged substances to pass through membrane. (Glucose, fructose, some vitamins)
76
Factors affecting rate of diffusion
Concentration gradient/ pressure gradient/ electrical gradient
Lipid solubility/ molecular size/ temperature
Thickness of membrane/ surface area
77
How does water move in osmosis?
Between lipid molecules
Through aquaporin channels (integral proteins)
78
What are sources of energy for active transport?
Hydrolysis of ATP
Energy stored in ionic concentration gradient (secondary active transport)
79
Examples of primary active transport
Sodium potassium pump: 2 potassium in, 3 sodium out. Created high concentration of potassium
Calcium pump: present in the membrane of ER, mitochondria and cell membrane. Involves uniport carrier.
Hydrogen potassium pump
80
What does secondary active transport depend on?
On concentration gradient of sodium.
Substance is transported along with sodium.
Sodium is transported only when glucose molecule is attached.
81
Types of transporters
Uniport: one molecule
Antiport: two molecules in opposite directions
Synport: co-transport (sodium+ glucose)
82
Describe gap junctions (giunzioni gap)
These are tubes that join 2 cells together. This connection allows transport of water and ions. The tubes also spread electrochemical signals that are produced by action potentials that occur in nervous system and in cardiac cells.
Gap junction channel (tube) is called connexon and is made of 6 membrane proteins called connexins.
83
Describe tight junctions (giunzioni strette)
A watertight seal. Prevent liquid from escaping between cells. Tight junction proteins called claudins.
Connections that form when 2 cells are squished up against one another. Cell membranes are connected while the contents are not. Impermeable layer between the cells.
Present in bladder, kidneys, intestines, so the fluids don’t leave the cells.
84
Describe desmosomes.
Cell membranes are connected by thread like substances that connect the cells across the space in between cells. These are adhesion proteins called cadherins. These hold the cells together, but do not allow fluids or materials to pass from the inside of one cell to the next. These connections are also attached to the cytoskeleton to help with structural support. Between the cells water can flow freely. These connections are present in skin and intestines. These ensure that cells in organs and tissues stretch (cardiac muscles and skin)
