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Cell structure Flashcards

1
Q

Cell theory

A
  1. All living things are made of cells
  2. Cells are the basic unit of life
  3. All cells come from pre-existing cells
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2
Q

Prokaryote vs Eukaryote (In terms of nucleus, organelles and number of cells)

A

Prokaryote - no cell nucleus, always unicellular, does not contain membrane bound organelles
Eukaryote - has a cell nucleus, can be uni or multi cellular, contains membrane bound organelles

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3
Q

Typical components of prokaryotes (6 things)

A
  1. Cell wall
  2. Plasma membrane
  3. 70S ribosomes
  4. Cytoplasm
  5. Plasmids
  6. Naked DNA in a loop (In nucleoid)
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4
Q

70S vs 80S ribosomes

A

70S - found in prokaryotes, smaller, lighter
80S - found in eukaryotes, larger, higher mass

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5
Q

Function of cell wall (3 points)

A

1) Maintain cellular structure
2) Prevent cell from bursting when osmotic pressure is higher inside cell
3) Protects against toxins

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6
Q

Function of plasma membrane (2 points)

A

1) Controls what enters and exits the cell
2) Separates cells interior from external environment - maintains internal chemistry

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7
Q

Function of cytoplasm (2 points)

A

1) Suspends contents of cell (e.g. ribosomes, ions, organic molecules)
2) Acts as a site for metabollic reactions

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8
Q

Function of ribosomes (1 point)

A

1) Synthesising proteins through translation

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9
Q

Function of Naked DNA in prokaryotes (2 points)

A

1) Contains information for protein synthesis
2) Expressing genes in replication

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10
Q

Funtion of plasmids in prokaryotes (1 point)

A

1) Contains pieces of DNA which can be transfered to other prokaryotic cells through horizontal gene transfer

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11
Q

Typical components of Eukaryotes (12 things)

A

1) Plasma membrane
2) Cytoplasm
3) Nucleus
4) Mitochondria
5) Golgi apparatus
6) 80S ribosomes
7) Smooth endoplasmic reticulum
8) Rough endoplasmic reticulum
9) Vacuole
10) Cytoskeleton
11) Vesicle
12) Lysosomes

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12
Q

Function of mitochondria (1 point)

A

1) Double membrane bound organelles which convert glucose to ATP through respiration

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13
Q

Function and structure of Nucleus (3 points)

A

1) Contains DNA associated with histone proteins and is organised into chromosomes
2) Contains nucleolus, which produces ribosomes
3) Has a double membrane which contains nuclear pores - allows small molecules like RNA, glucose and ions to pass through

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14
Q

Function of SER (1 point)

A

1) Produces and stores lipids, including steroids

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15
Q

Function of RER (1 point)

A

1) Has ribosomes attached to surface which produce proteins

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16
Q

Function of Golgi apparatus (1 point)

A

1) Process and package proteins, which are released in golgi vesicles

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17
Q

Function of vesicles (1 point)

A

1) Small sac which transports and releases substances made in the cell by fusing with cell membrane

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18
Q

Function of vacuole (2 points)

A

1) Acts as a store for substances
2) Maintains osmotic balance in cell

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19
Q

What is cytoskeleton composed of and what is its function?

A

1) A system of protein fibres called microtubles and microfilaments
2) Help to hold organelles in place and maintain structure of cell

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20
Q

Compartmentalisation

A

The process by which organelles are packaged into membranes to allow interiors to have different conditions to rest of cytoplasm

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21
Q

Advantages of compartmentalisation (4 points)

A
  1. Metabolites (substances involved in metabolism) and enzymes are closer so higher chances of successful collision
  2. Damaging substances e.g. toxins can be isolated and expelled so they don’t spread
  3. Areas of membranes can be dense in certain proteins to increase efficiency of specific proccess
  4. Can maintain conditions e.g. temp and pH for a specific reaction and enzyme
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22
Q

Structure of phospholipids (found in membranes)

A
  • Two layers of phospholipids
  • Outer layer = hydrophilic head face outwards and hydrophobic tails face inwards
  • Inner layer = hydrophobic tails face inward towards other tails and hydrophobic heads face towards interior of cell
23
Q

2 examples of unicellular organisms where processes of life can be studied

A

Parecium - eukaryote
Chlamydomonas - eukaryote

24
Q

How do parecium and chlamydomonas exchange matter with environment?

A

Parecium - waste products excreted through anal pore
Chlamydomonas - oxygen from photosynthesis diffuses out of cell membrane

25
How do parecium and chlamydomonas obtain energy and matter?
Parecium - eats small unicellular organisms Chlamydomonas - is an autotroph so uses photosynthesis to obtain energy
26
How do parecium and chlamydomonas carry out metabolic reactions?
Cells contain enzymes to catalyse reactions - in cytoplasm for both and also chloroplasts only in chlamydomonas
27
How do parecium and chlamydomonas grow?
Both grow until maximum surface area to volume ratio, then they divide
28
How do parecium and chlamydomonas respond to their environments?
Parecium - controls cilia beating to move according to enviroment Chlamydomonas - Light sensitive eye spot allows them to sense light and move towards it using flagella
29
How do parecium and chlamydomonas reproduce?
Both - nucleus divides via mitosis to reproduce asexually. Two can also fuse before dividing to carry out sexual reproduction
30
How do parecium and chlamydomonas maintain homeostasis?
Both - excess water collected to a contractile vacuole and expelled to maintain osmotic pressure
31
Describe features of striated muscle fibers that make them an atypical cell.
Eukaryotic cell which contains more than one nucleus
32
Describe features of red blood cells that make them an atypical cell.
Eukaryotic cell which doesn't have a nucleus (in adults)
33
Describe features of aseptate fungal hyphae that make them an atypical cell.
Has continuous cytoplasm and is not clearly divided into individual cells
34
Describe features of phloem sieve elements that make them an atypical cell.
- No nucleus - Little cytoplasm - Few organelles
35
What is the cell wall made of in fungi, plants and bacteria cells?
Fungi - chitin Plants - cellulose Bacteria - peptidoglycan
36
What are the advantages of compartmentalisation of nucleus?
- Post transcriptional modifications can occur (parts of mRNA are removed after transcription before it leaves nucleus) - Allows cytoplasm to send ligands (i.e. hormones) to nucleus and tell it to produce more or less specific proteins depending on conditions
37
Which organelles have a double membrane in eukaryotic cells?
- Nuclei - Mitochondria - Chloroplasts
38
Which organelles have no membrane?
Ribosomes, centrioles, nucleolus
39
Which cell structures are not considered organelles?
Cytoplasm, cytoskeleton, cell wall
40
How were cell components first separated?
1) Cells disrupted with a homogeniser (blender) 2) Centrafuged step by step, removing the pellet between each centrafuge. The centrafugal force increases each time to separate less dense organelles
41
Lysosomes
Organelles which hydrolize biological polymers and contain high concentration of enzymes.
42
What is an example of compartmentalisation in eukaryotic cells and how it is beneficial?
Lysosomes contain acid hydrolases (enzymes which hydrolize molecules and work best in acidic pH) so interior is maintaned at 5 pH by actively producing H+ ions Acidic interior protects against uncontrolled digestion of cytoplasm - even if membrane breaks down acid hydrolase would not work in neutral pH of cytoplasm
43
How does compartmentalisation benefit phagosome (phagocytic vacuole)?
- When a cell engulfs a particle, it encloses it in a phagosytic vacuole - which fuses with a lysosome to form a phagolysosome - it is then digested by hydrolitic enzymes
44
How are outer and inner membranes, cristae, IM space and matrix adapted to their functions within the mitochondria?
Outer membrane - has transport proteins to move key materials for respiration Inner membrane - has ETC and ATP synthase Cristae - folds increase SA:Vol ratio IM space - small space maximises electrochemical gradient in ETC Matrix - contains specific enzymes for Krebs
45
How are thylakoids, Grana, photosystems, stroma and lamellae adapted to their functions witin chloroplasts?
Thylakoids - small internal volume to maximise electrochemical gradient Grana - thylakoid aranged into stacks to increase SA:Vol of membrane Photosystems - pigments organised into photosystems in thylakoid to maximise light absorption Stroma - central cavity contains appropriate enzymes and pH for Calvin cycle Lamellae - connects grana to maximise photosynthesis efficiency
46
What are the components of the nucleus?
Nuclear envelope made of a double membrane with nuclear pores in it, Nucleoplasm, Chromatin (looks like a ball of hair made of DNA), nucleolus.
47
What are the two ways that substances can be released from the golgi apparatus?
Constitutive secretion - released immediately in a vesicle Regulatory secretion - strored in secretory vesicles for a sustained release triggered by ligand binding to specific receptor
48
What are vesicles?
Membrane - wrapped containers which transport materials
49
How does clathrin aid in the formation of vesicles?
- Protein coat which forms a lattice around a part of the membrane with the substance to be transported - Causes it to fold and wrap into a vesicle - Once vesicle is formed, clathrin dissociates
50
What is receptor mediated endocytosis?
Substance which needs to be transported into cell acts as a ligand and activates adaptor proteins which cause clathrin to bind and vesicle formation to begin.
51
Function and structure of ligaments
Connects bone to bone - elastic to allow for movement
52
Function of synovial fluid
Fluid found between bones which acts as a shock absorber
53
What are joints?
Site of junction between two or more bones
54
Function and structure of tendons
Attaches muscle to bone and are inelastic

Biology IB (13 decks)

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