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A2.2 cell structure (SL) Flashcards

1
Q

What are the 3 basic principles of cell theory?

A

1) All living things are made of cells

2) Cells are the smallest unit of life

3) Cells come only from other cells

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2
Q

Define “magnification”

A

how much larger an object appears compared to its real size

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3
Q

Define “Resolution”

A

the smallest interval distinguishable by the microscope, which then corresponds to the degree of detail visible in an image created by the instrument

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4
Q

Define “Membrane”

A

a bilayer formed from phospholipids as a consequence of their hydrophobic and hydrophilic regions

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5
Q

Explain what a plasma membrane is

A

Every cell has a membrane barrier separating the interior from its surroundings

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6
Q

Define “cytosol”

A

the liquid part of the cytoplasm

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7
Q

Define “cytoplasm”

A

Gel-like fluid substance made of water and many dissolved solutes such as salts, fatty acids, sugars, amino acids and proteins e.g. enzymes (needed to carry out the metabolic processes required to keep the cell alive; if these molecules not dissolved in water → not able to perform their function)

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8
Q

What is the relationship between solutes, solvents and solutions? Give examples for each.

A

Solute + Solvent = Solution

  • solute e.g. glucose, oxygen
  • solvent e.g. water
  • solution e.g. glucose solution
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9
Q

What is evidence of universal common ancestry?

A

The use of the DNA code across all forms of life (today all living organisms use DNA as the genetic material)

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10
Q

Differences between prokaryotic and eukaryotic DNA?

A

Prokaryotic DNA is not in a nucleus and does not wrap around histone proteins

  • if taken out, its a loop

Eukaryotic DNA is found in the cell nucleus and wraps around histone proteins

  • if taken out, can be stretched until it becomes linear (straight line)
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11
Q

Nucleosome is DNA wrapped around how many histone proteins

A

8

Nucleosome is DNA wrapped around 8 histone proteins

only eukaryotes have histones because their DNA is longer than prokaryotes

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12
Q

Why can’t prokaryotes carry out aerobic respiration?

A

Because they don’t have mitochondria

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13
Q

Explain what exocytosis is (not definition)

A

Export of things outside the cell

Using vesicles

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14
Q

Define “Organelles” + examples

A

membrane bound units that compartmentalised functions in the cell

e.g. nucleus, mitochondria

only eukaryotes have them, not prokaryotes

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15
Q

Why compartmentalise?

A

1) Control concentrations of chemicals that are needed or produced by the organelles in their metabolic reactions

2) mRNA can be modified after transcription before it leaves the nucleus

3) Avoid enzymes (e.g. lysozymes in lysosomes from destroying the cell. It also allows phagocytic vesicles to be formed.)

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16
Q

Why does lysosome need to be bounded by a cell membrane?

A
  • because it contains enzymes
  • will digest organelles e.g. ribosomes, mitochondria
  • killing cells from within :(
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17
Q

What is the function of Golgi Apparatus?

A
  • The Golgi modifies polypeptides into their functional state
  • The Golgi sorts, concentrates and packs proteins into vesicles
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18
Q

Vesicles of Golgi Apparatus are dispatched to?

A
  • within the cell, to organelles called lysosomes
  • the plasma membrane of the cell
  • secretion to the outside of the cell via exocytosis

fuses with the plasma membrane & released out of the cell

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19
Q

Function of cytoskeleton

A
  • Helps cells maintain their shape, organises cell parts and enables cells to move and divide
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20
Q

List the components that work together to form the cytoskeleton and their functional use

A
  • Microtubules (movement)
    • Actin filaments (movement)
    • Intermediate filaments (structural)
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21
Q

What is the name of the polymers of a protein which forms part of the cytoskeleton

A

tubulin

polymers of a protein called tubulin and form part of the cytoskeleton

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22
Q

Function of microtubules

A

Used for intracellular transport of organelles and the separation of chromosomes during mitosis

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23
Q

Describe the structure of Centrioles (MTOC)

A

paired cylindrical-shaped organelles composed of nine groups of three microtubules organised with radial symmetry

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24
Q

What is the function of Centrioles/MTOC (microtubule organising centre)

A
  • arrangement of the mitotic spindle during cell division
  • serve as anchor points for microtubules in the cytoplasm and for cilia and flagella (when modifiied to become a basal body)
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25
What is cilia?
- extensions from the cell surface which aid in cell movement
26
How are cilia formed?
formed from modified centrioles called a basal body
27
How does cilia work?
- Cilia beat in coordination with each other - back and fourth beating
28
How do you tell apart cilia and flagella from their protrustions?
Flagella: If protrusions are longer and less numerous (usually only one or two) Cilia: if the protrusions are short and numerous
29
How to flagella move?
flagella moves independently from each other
30
Describe the motion of sperm movement?
Sperm: propeller-like motion (spiral)
31
Give 3 examples of single membrane organelles
- lysosome - ER - golgi
32
Give 3 examples of double membrane organelles
- chloroplasts - nucleus - mitochondrion
33
What is chromatin?
Form of chromosome before it divides
34
Function of nucleolus
makes ribosomes
35
What are nuclear pores?
nuclear pores can be open and shut → can control when mRNA goes out mRNA copied from DNA to go out of ribosome pores needed for mRNA to pass through (on the surface of the nucleus)
36
Define "Plastids"
Plastids: A family of organelles with two outer membranes and internal membrane sacs
37
Define "Cell wall"
Cell wall: a rigid layer outside the plasma membrane to strengthen and protect the cell Vacuole: A flexible fluid-filled compartment surrounded by a single membrane Centrioles: Cylindrical organelles that organise the assembly of structures composed of microtubules Undulipodia: Cilia and flagella used to generate movement of a cell or movement of fluid adjacent to a cell
38
Define "Vacuole"
Vacuole: A flexible fluid-filled compartment surrounded by a single membrane
39
Define "Centrioles"
Centrioles: Cylindrical organelles that organise the assembly of structures composed of microtubules
40
Define "Undulipodia"
Undulipodia: Cilia and flagella used to generate movement of a cell or movement of fluid adjacent to a cell
41
Explain the meaning of "septate" and an example of an organism with this feature
multinucleated (more than one nuclei in one cell) example: Aseptate fungal hyphae
42
Explain the cell structure and function of RBCs
- No nucleus = more space to carry haemoglobin (for oxygen) - Biconcave / flattened disc shape - Diffusion: O2 in, CO2 out
42
What is an alternate name of RBCs?
Erythrocyte
43
Give examples of eukaryotes that have atypical cell structures
- Aseptate fungal hyphae - Skeletal muscle (striated muscle) - RBC - Phloem sieve tube elements
44
What is the function of flagellum?
movement
45
Name the parts of a prokaryotic cell
Functions of prokaryotic cell parts - Flagellum - Ribosomes - Pilli - Cell wall - Cytoplasm - Nucleoid - Plasma membrane
46
What is the function of ribosomes?
protein synthesis
47
What is the function of pilli?
attachment, DNA transfer
48
What is the function of cell wall?
protective coating, can be Gram-positive or Gram-negative Peptidoglycan → chemical that is different in gram positive and gram negative cell wall of Bacteria - gram positive - thick layer of Peptidoglycan - gram negative - thin layer of Peptidoglycan - also has outer membrane beyond the Peptidoglycan
49
What is the function of cytoplasm?
contains enzymes for metabolism
50
What is the function of nucleoid?
region containing closed-loop DNA
51
What is the function of plasma membrane
controls entry and exit of substance
52
What don't prokaryotes have mitochondria?
- prokaryote → no organelles - also don’t need mitochondria bc use anaerobic respiration
53
Describe the shape of Bacillus (bacteria)
rod shaped
54
Define "homeostasis" and give an example
iving organisms keep their internal environments within a certain range (they maintain a stable internal condition), despite changes in their external environment e.g. by keeping concentrations of water and minerals within certain levels
55
Define "metabolism"
the sum of all the chemical reactions in a cell
56
Why are viruses not considered self-sustaining life? (link to metabolism)
Viruses lack metabolism, a reason they are not considered to self-sustaining life
57
Define "anabolic reaction"
smaller molecules join to make larger ones → use energy, endergonic
58
Define "catabolic reaction"
large molecules are broken down into smaller ones → release energy, exergonic
59
Explain what a catalyst is
speeds up chemical reaction by reducing the activation energy and it does not get used up
60
Define "nutrition"
all life obtains energy and matter
61
Define "autotrophs"
use external energy sources (usually the sun) to synthesise carbon compounds from simple inorganic substances
62
Define "heterotrophs"
use carbon compounds obtained from other organisms to synthesise the carbon compounds that they require
63
Give an example of a phototroph
photoautotroph → plants - photo = light
64
Give an example of a chemoautotroph
- chemo = chemical - e.g. volcanos under the sea, bacteria who live down there use energy from deep vents
65
Define "movement"
adaptions for movement are a universal feature of living organisms
66
What do sessile organisms refer to?
organisms that stay in one place
67
What do motile organisms refer to?
organisms that are mobile
68
Define "excretion"
a process in which metabolic waste is eliminated from an organism
69
Give an example of excretion in humans
primarily occurs via lungs and kidneys - co2 created by both aerobic & anaerobic respiration - aerobic: oxygen + glucose → water + carbon dioxide - anaerobic: glucose → lactic acid; lactic acid broken down by oxygen into water + carbon dioxide
70
Give an example of excretion in plants
- excretion occurs via leaves, roots and stem - photosynthesis
71
Give an example of excretion in unicellular organisms
occurs through the cell membrane, which is one reason cells must have a large surface area to volume ratio
72
Explain what egestion is
removal of undigested food
73
Define "growth"
increase in the size and mass of an organism
74
Define "development"
is the transformation of the organism through its lifespan
75
What does "response to stimuli" mean
- all life can recognise and respond to changes in environmental conditions - even single celled organisms can recognise what is going on around them, and respond to changes in the environment
76
State the types of receptors and what their stimuli is
chemoreceptors: chemical concentration of substances baroreceptors: pressure thermoreceptors: temperature photoreceptor: light energy
77
How do sexual and asexual reproduction differ?
- Sexual reproduction: involves two parents and the fusion of haploid sex cells from each parent - Asexual reproduction: involves only one parent (mitosis)
78
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biology hl (19 decks)

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