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Year 12 Bio > 2.2 - 2.3 prokaryotic cells & mitosis > Flashcards

2.2 - 2.3 prokaryotic cells & mitosis Flashcards

1
Q

Gram positive bacteria is made of ..

A

-Thick layer peptidoglycan in their cell walls
-Teichoic acid trapped in thick layer

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2
Q

Gram negative bacteria is made of ..

A

-Thin layer peptidogylcan between 2 layers of membrane
-no teichoic acid
- outer membrane contains lypopolysaccharides

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3
Q

2 main types of bacteria can be distinguished by

A

Gram staining

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4
Q

How does gram staining work ?

A
  1. Add purple crystal violet / iodine complex all cells appear purple as they take in stain
  2. Add alcohol to decolorisation , only GN bacteria loose colour as layer of lipopolysaccharides is dissolved & can’t hold stakn
  3. Add red safranin counterstain to stain GN bacteria red. counterstain not seen on gram- positive bacteria because of the darker crystal violet stain.
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5
Q

Other than gram staining how else can bacteria be classified

A

Shape
Respiratory requirements

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6
Q

Respiratory requirements:
Obligate aerobes
Facultative aerobes
Obligate anaerobes

A

Need oxygen for respiration
Use oxygen if available but can manage without
Can only respire in absence of oxygen

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7
Q

How does the beta lactam (penicillin) antibiotic work
Why are they more affective against gram pos

A

It attacks gram positive bacteria by inhibiting the formation of cross links in the peptidoglycan layer of cell wall
- water moves into cell my osmosis , cell bursts

They have thick pep layer so the cell wall can be affected

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8
Q

How does the Glycopeptide antibiotic work

A

-They’re large polar molecules
- affective against gram positive
- difficult to penetrate outer membrane layer of gram neg
-

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9
Q

How does polypeptide antibiotics work?

A
  • rarely used as can have serious side effects
  • affective with - as they interact w phospholipids of outer membrane
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10
Q

What happens during the g1 interphase stage of mitosis?

A

Duplication of organelles like mitochondria
- cell growing in size and making of proteins

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11
Q

What happens in the s phase of interphase (mitosis)?

A
  • chromosomes replicate becoming double stranded chromatids
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12
Q

What happens in the G2 phase of interphase (mitosis)?

A

Organelles and other materials needed for cell divisions are synthesised

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13
Q

When a cell starts to actively divide …

A

The chromosomes become shorter and denser allowing them to take up stains easier and be identified

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14
Q

When dna condenses (becomes shorter and denser ) how is it packaged efficiently ?

A

Dna winds around histones to produce nucleosomes
These intercatc o produce more coiling then they super coil

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15
Q

The cell cycle is controlled by …

A

Cyclins which attach to enzymes called cyclin dependent kinases

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16
Q

what takes place in the prophase phase of mitosis?

A

-dna condenses , chromsomes become visible
-nuclear membrane breaks down
-as centrioles divide and move to either pole spindle fibres form

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17
Q

what takes place in the metaphase phase of mitosis?

A

spindle fibres attach to centomeres
Chromosomes are lined up at cell equator by sf

18
Q

what takes place in anaphase phase of mitosis?

A

centromeres separated , sc pulled apart, sister chromatids move to opp poles,

19
Q

telpohase?

A

-nuclear envelopes form around 2 sets of chromosomes
-nucleoli reforms
- chromosomes decondense , lengthen can’t see

20
Q

cytonkinesis?

A

2 identical daughter cells formed

21
Q

what is assexual reproduction

A

reproduction involving one parent and produces genetically identical offspring

22
Q

these methods of assexual reproduction rely on mitosis:

binary fission

producing spores

A

used by bacteria, splitting of one individual to form 2 new ones, causes exponential growth

fungi, plants, production of assexual spores that can grow into new individuals , spread over large distances

23
Q

these methods of assexual reproduction rely on mitosis:

regeneration

producing buds

A

lizards, starfish, fungi – use of mitosis to regrow a body part that has been lost

yeast cells, hydra – an outgrowth from a parent organism which produces a smaller but genetically identical individual

24
Q

these methods of assexual reproduction rely on mitosis:

vegatative propagation

parthogenesis

A

Producing identical plants from part of a plant

unfertilised egg cell develops into new indiviudal

25
Q

the structure of viruses is composed of..

A

capsid coat which is made of repeating units called capsomeres
-a lipid enevelope derivered from host cell membranes
-nucleic acid

26
Q

how do viruses attach to host cells..
why dont viruses attach to all cells

A

through virus attachment particles
viruses attach to specific molecules on cells surface

27
Q

how can types of viruses be classified

A
  1. dna viruses
  2. rna viruses (+ and - ssRNA)
  3. rna retroviruses
28
Q

DNA viruses -

RNA retroviruses -

A

viral dna acts as template for cell to make mRNA then viral proteins

ssRNA, makes enzyme called reverse transcriptase converts rna to dna , cell makes mrna , cell makes viral protein

29
Q

ssRNA viruses:

positive
negative

A

+ = rna used as mRNA for cell to directly make viral proteins
- = ssRNA , rna transcribed to form mRNA, cell makes viral protein

30
Q

lambda phage -

tobacco mosaic virus -

A

-dna no envelope
- positive ssRNA, no envelope

31
Q

ebola
HIV

A
  • positive ssrna, lipid envelope
  • rna retovirus, lipid envelope
32
Q

how does the lytic pathway work

A
  • attachment using vaps
  • entry of viral gm
    -replication of vgm and production of viral prot
    -assmebly of new viral particles/viruses
    -lysis of host cell
33
Q

how does the lysogenic cycle work?

A

attachement (vaps)
-entry of vgm which is inserted into bacterial nucleoid
-replication of vgm every time bac cell undergoes binary fission
- if the amount of reperessor protein falls , dna forms own circle entering lytic cycle

34
Q

why cant viruses be treated with antibiotics?

antiviral drugs target virus replication by :

A

they arent living cells

  1. targetting receptors by which viruses recognise their host cell
  2. targetting enzymes that help translate / replicate viral dna or rna
35
Q

vaccinations develop..

A

immunity to a disease
gloves, facemasks, vaccines

36
Q

Why are viruses not affected by antibiotics

A
  • viruses aren’t living cells
  • viruses don’t have cell wall
37
Q

Define growth

A

The permanent increase in the mass of an organism

38
Q

Why can measuring mass be difficult ?

A

The water content of cells can vary greatly
- animals can also be carrying varying amounts of faecal matter in their bodies

39
Q

What’s the most accurate way of measuring growth

A

Measuring dry mass , it shows the amount of biological material present

40
Q

Growth in plants

A

Meristems where mitosis takes place
Cells differentiate
Elongation of cells

Year 12 Bio (5 decks)

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