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Biology > Module 2: Cells And Microscopy > Flashcards

Module 2: Cells And Microscopy Flashcards

Microscopy, Cell structure, Cell Membranes, Transport Across cell membranes, Cell division, Specialisation and Organisation

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1
Q

Function of Microtubules

A

Involved in transport of organelles

Make up spindle fibres for cell division

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2
Q

Function of microfilaments

A

Mechanical strength

Link membrane proteins to cytoplasm proteins

Provide supporting framework

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3
Q

Protein synthesis

A

1) DNA code to produce protein is converted to mRNA

2)mRNA escapes through nuclear pore

3)mRNA attach to ribosome, protein is synthesised. Ribosome attach to RER. Folded + processed here

4)proteins packaged into vesicles + transported to golgi apparatus

5)proteins are structurally modified. Carbohydrate chains added

6)proteins leave golgi apparatus in a transport vesicle towards the plasma membrane

7)vesicle fuses with cell membrane. Protein is released by Exocytosis

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4
Q

Magnification equation

A

Image size / actual size

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5
Q

Define Resolution

A

The shortest distance between two objects, so that they can still clearly be seen separately

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6
Q

Why do we stain samples?

A

A stain colours some parts of a cell more clearly than others.
E.g: methylene blue stains nucleus stronger blue than cytoplasm.

A stain colours certain parts of a cell when it reacts with chemicals in it
E.g: iodine colours potato starch purple/blue black

This makes them more visible

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7
Q

Maximum Magnifican of:

Light microscopes

Scanning Electron

Transmission Electron

A

Light: x1500

Transmission: x1,000,000 +

Scanning: x500, 000

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8
Q

Prokaryote

A

A single-celled Organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelle

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9
Q

Function of Cholesterol in the plasma membrane

A

Gives stability and fluidity

Pulls areas of membrane together

Stops phospholipids from grouping closely and crystallising

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10
Q

Structure andFunction of Channel proteins in membrane

A

Provides hydrophilic channel that allows passive movement of Polar molecules and ions

Held in place by interaction between hydrophobic core and hydrophobic R-groups of proteins

Intrinsic

Some are Gated

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11
Q

Function of carrier proteins in the membrane

A

Involved in both passive and active transport

Shaped to fit specific Molecules

Opens at other end

Flip-flop movement

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12
Q

Diffusion

A

The net movement of molecules from a region of high concentration to a region of lower concentration down a concentration gradient

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13
Q

What is Facilitated diffusion

A

Where protein carrier molecules within the membrane assist the passage of substances across the membrane in the direction of their concentration gradient

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14
Q

Factors affecting the rate of diffusion

A

Temperature

Concentration gradient

Stirring/movement

Surface area

Diffusion pathway

Size of molecule (smaller molecule=less energy needed to move them)

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15
Q

Active Transport

A

The movement of molecules against the concentration gradient. It requires energy in the form of ATP

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16
Q

Bulk Transport (in active transport)

A

moving large amounts of materials in or out of the cells

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17
Q

Process of Endocytosis

A

-Materials moved into cell in ‘bulk’
-membrane surrounds material, breaks apart and moves into cell
-Enzymes in the cell break down the material, allowing it to pass through the membrane into the cell

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18
Q

Exocytosis process

A

-Material is transported to cell membrane in secretory vesicle
-vesicle fuse with cell membrane
-release their contents outside of the cell

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19
Q

Why is active transport needed?

A

-Carries substances faster
-To accumulate substances into and out of the cell

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20
Q

Osmosis

A

the Net movement of water from a region of high water potential to a region of lower water potential through a selectively permeable membrane

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21
Q

define Water Potential

A

The tendency of water molecules to move from one place to another

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22
Q

What is the Water potential of pure water?

A

ZERO

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23
Q

Water potential is the measure of free…

A

free energy available for water molecules to move.
This free energy is greatest in pure water.

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24
Q

Hypotonic solution

A

Solution is less concentrated than cell

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25
Q

Isotonic solution

A

Solution has same concentration as cell

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26
Q

Hypertonic Solution

A

Solution has higher concentration than cell

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27
Q

Animal cell placed in Isotonic solution

A

-No Net gain or loss of water
-The cell’s water content remains steady

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28
Q

Animal cell placed in hypertonic solution

A

-Cells lose water by osmosis and shrink
-Described as being CRENATED

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29
Q

Animal cells placed in Hypotonic Solution

A

-Cells gain water by osmosis and Burst
-Bursting of red cells when placed in Hypotonic solution is called Haemolysis

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30
Q

Fully Turgid Plant cell placed in Hypotonic solution

A

-net movement of water into the cell by osmosis
-Protoplast swells and presses against cell wall

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31
Q

Plant Cell placed in Isotonic solution

A

-Cell displays incipient Plasmolysis. This is where the membrane is just beginning to pull away from the cell.
-Protoplast ceases to press against cell wall

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32
Q

Plant cell placed in Hypertonic Solution

A

-Net movement of water out of the cell by osmosis
-Protoplast shrinks
-Protoplast pulled completely away from cell wall
-Cell is fully plasmolysed (flaccid)

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33
Q

What are the 6 stages of cell division?

A

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

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34
Q

What happens at Interphase in mitosis?

A

Each chromosome is replicated

35
Q

What happens at Prophase in Mitosis?

A

Chromosomes become Condense
. Able to see pair of sister chromatids / chromosomes have become visible

Nuclear envolope and nucleolus breaks down / dissapearred

Centriole goes to each pole to form spindle

36
Q

What happens at Metaphase in Mitosis?

A

Chromosomes move to equator and centromeres attach to spindle

37
Q

What happens at Anaphase in Mitosis?

A

Replicated sister chromatids that make up chromosome are separated

Centromere splits / Chromatids are separating

Each sister chromatid becomes a chromosome (identical to parent cell)

Spindles shorten and move sister chromatids towards poles

38
Q

What happens at Telophase in Mitosis?

A

Chromosomes reach new poles

New nuclear envolope reforms around downs centre of cell

Spindle breaks down

Chromosomes uncoi

Cytokinesis / cell is starting to divide

39
Q

What is Cytokinesis?

A

When the cell splits in two, membrane splits

40
Q

Prophase 1 Meiosis

A

Homologous chromosomes pair up -> Bivalent
*Crossing over (swapping alleles)

41
Q

How is Metaphase 1 in Meiosis different to mitosis?

A
  • the homologous pairs of chromosomes assemble along equator instead of the individual chromosomes

Independent assortment of homologous chromosomes occurs (the way the chromosomes align along the equator e.g: Fathers chromosome on one side of equator, Mother on other. A mix..)

42
Q

Chiasmata

A

The point of breakage where alleles between homologous chromosomes are swapped

43
Q

How is Anaphase 1 in Meiosis different to mitosis?

A

The homologous chromosomes are pulled to opposite poles and chromatids stay joined together/ NO separation of centromere

44
Q

Telophase II Meiosis

A

In total, 4 haploid cells (gametes)

45
Q

How is Telophase 1 in Meiosis different to mitosis?

A

The reduction of chromosome number from diploid to haploid is complete

n=2

46
Q

how many cells are produced from meiosis?

A

4 unidentical cells (due to chromosomes crossing over)

47
Q

What 3 stages in meiosis lead to genetic variation

A

1) Prophase 1 -Crossing over of homologous chromosomes (swapping alleles)

2)Metaphase 1- independent assortment of homologous chromosomes (arrangement along equator)

3)Metaphase 2- Independent assortment of sister chromatids

48
Q

What is a Stem cell

A

An unspecialised cell that can differentiate into different types of cell

49
Q

What is a Totipotent stem cell

A

Can make all cell types

Zygote and early embryo cells are like this

50
Q

What is a Pluripotent stem cell

A

Capable of producing all cells derived from a particular germ layer: ectoderm, endoderm, mesoderm.

Present in early embryos

51
Q

What is a multipotent stem cell

A

Can make a restricted range of related cell types
E.g: haemopoietic stem cells make red, white blood cells and platelets

52
Q

What can cambium differentiate into

A

Xylem and phloem

53
Q

What is a tissue

A

Collection of cells that are similar to each other and perform a common function

54
Q

What is an organ

A

A collection of tissues working together to perform a particular function

55
Q

What is an organ system

A

A number of organs working together to perform an overall life function

56
Q

How is a palisade cell specialised for its function

A

Lots of chloroplast to absorb large amounts of light for photosynthesis

57
Q

How is squamous Epithelial cell specialised for its function

A

-squat/flat cells
-once cell thick

To create short diffusion distance

58
Q

How are elastic fibres used in airways

A

Recoil of alveoli

59
Q

What is the cell wall of a prokaryote made of

A

Peptodiglycan

60
Q

What is the cell wall of plants made of

A

Cellulose

61
Q

What is the cell wall of fungi made if

A

Chitin

62
Q

Suggest why sexual reproduction in Hydra usually occurs in the winter. When conditions are unfavourable

A

(some offspring) might survive unfavourable
conditions 
(some) offspring have useful alleles 
(named) unfavourable conditions mean (all) offspring
might die (if asexual) 

63
Q

Mitosis and meiosis are important in the life cycles of organisms.
(a) Hydra is a small animal that lives in fresh water. When environmental conditions are
favourable, Hydra reproduces asexually. Large numbers of offspring can be produced in this
way.

Suggest why Hydra reproduces asexually when conditions are favourable.

A

genetically identical offspring 
offspring produced , rapidly / in large numbers 
(all) offspring will , find conditions favourable / have
same adaptations 

64
Q

show the main differences in structure between glucose and
starch.

A

Glucose Starch
monomer polymer 
monosaccharide polysaccharide 
no glycosidic bonds glycosidic bonds 
C6H12O6 / more H and O C6H10O5 / less H and O

65
Q

what are homologous chromosomes

A

Homologous = same

A pair of chromosomes with the same structure and genes, one from mum and one from dad

66
Q

Phospholipids bilayers act as a barrier to most ______-_____ substances (the non-polar fatty acid tails prevent ____ or ____ from passing across the membrane)

A

water-soluble

polar molecules or ions

67
Q

There are three main receptor types:

(the roles)

A

Signalling receptors for hormones and neurotransmitters

Receptors involved in endocytosis

Receptors involved in cell adhesion and stabilisation (as the carbohydrate part can form hydrogen bonds with water molecules surrounding the cell

68
Q

Transport proteins create ______channels to allow ____ + _____ molecules to travel through the membrane

A

hydrophilic

ions and polar

69
Q

The permeability of cell membranes is affected by different factors or conditions, such as:

A

Temperature
Solvent concentration

70
Q

How do organic solvent conc. affect the structure and permeability of the plasma membrane

A

Organic solvents can increase cell membrane permeability as they dissolve the lipids in the membrane, causing the membrane to lose its structure

71
Q

As temperature increases, lipids become more ____
This increased fluidity reduces the _____ of the cell membrane as a barrier to polar molecules, meaning polar molecules can pass through

A

fluid
effectiveness

72
Q

At higher temperatures, any diffusion taking place through the cell membrane will also occur at a _______(due to increased kinetic energy)

A

higher speed

73
Q

At higher temperatures, any diffusion taking place through the cell membrane will also occur at a _______(due to increased kinetic energy)

A

higher speed

74
Q

How does increasing temperature effect the permeability and structure of the plasma membrane (in terms of proteins)

A

At a certain temperature (often around 40°C) many proteins (including those in cell membranes) begin to denature
This disrupts the membrane structure, meaning it no longer forms an effective barrier
As a result, substances can pass freely through the disrupted membrane
This process is irreversible

75
Q

How does Surface Area effect the rate of diffusion

A

A larger surface area which diffusion is taking place, the greater the number of ions or molecules that can cross it at one moment, therefore the faster it diffuses

76
Q

G1 CHECKPOINT

A
  • chromosomes are checked for damage. If damage is detected then the cell does not advance into the S phase until repairs have been made
77
Q

Checkpoint During S phase

A
  • chromosomes are checked to ensure they have been replicated. If all the chromosomes haven’t been successfully replicated then the cell cycle stops
78
Q

G2 phase checkpoint

A

During G2phase- an additional check for DNA damage occurs after the DNA has been replicated . The cell cycle will be delayed until any necessary repairs are made

79
Q

Metaphase checkpoint

A

During metaphase- the final check determines whether the chromosomes are correctly attached to the spindle fibres prior to anaphase

80
Q

The movement from one phase to another is triggered by chemical signals called…….

A

Cyclins

81
Q

G1 phase

A

G1phase–Gstands forgrowth

Cells make the RNA, enzymes and other proteins required for growthduring the G1phase

82
Q

S phase of interphase

A

TheDNA in the nucleus replicates

Synthesis of DNA

Identical sister chromatids are made

83
Q

G2 phase cell cycle

A

During the G2phase, thecell continues to grow and the new DNA that has been synthesised is checkedand any errors are usually repaired

Other preparations for cell division are made (eg. production of tubulin protein, which is used to make microtubules for the mitotic spindle)

Biology (45 decks)

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