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bio > cells, viruses and reproduction (2) > Flashcards

cells, viruses and reproduction (2) Flashcards

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Biology 101 flashcards
1
Q

name the 6 features of prokaryotic cells

A

nucleiod
plasmids
70s ribosomes
cell wall
pili
flagella

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2
Q

what is a nucleon

A

an irregular shaped region of cytoplasm
where a loop of DNA is located

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3
Q

what are plasmids

A

rings of DNA found in some bacterial cells
contains non-essential genes

they can also be used for genetic modification

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4
Q

what are ribosomes

A

the site of protein synthesis

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5
Q

what is the cell wall

A

peptidoglycan cell wall provides strength and support
may have a slime capsule to prevent cessation

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6
Q

what are pili

A

hairs which help them attach themselves

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7
Q

what is the flagella

A

a tail like feature which allows for movement

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8
Q

outline the process of gram staining

A

stain the culture with crystal violet
rinse

add iodine (then remove)
add alcohol
counterstain with red safranin

dry + examine under microscope

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9
Q

explain the results of gram staining

A

gram positive stains purple
- thick peptidoglycan layer (insoluble in alcohol)

gram negative stains pink
- thin peptidoglycan layer (soluble in alcohol)

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10
Q

why do some bacteria react differently to antibiotics?

A

some antibiotics inhibit peptidoglycan formation
e.g. penicillin

  • this doesn’t work on gram negative as they have a thin peptidoglycan layer + an outer membrane
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11
Q

role of nucleus

A

stores genetic information + controls cell activities

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12
Q

role of nucleolus

A

the site of ribosomes production

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13
Q

role of the rough ER

A

many ribosomes attached for protein synthesis + transport

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14
Q

role of the smooth ER

A

the site of lipid synthesis

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15
Q

role of mitochondria

A

the site of respiration

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16
Q

role of centrioles

A

involved in cell division

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17
Q

role of lysosomes

A

contain digestive enzymes e.g. hydrolytic enzymes

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18
Q

role of the golgi apparatus

A

processes proteins and lipids + produces lysosomes

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19
Q

role of the cell wall

A

provides protection + support

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20
Q

role of chloroplasts

A

contains chlorophyll for photosynthesis

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21
Q

role of the vacuole

A

stores stuff e.g. cell sap in plants

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22
Q

role of tonoplasts

A

the vacuoles membranes
which regulates the movement of ions

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23
Q

why are specimen stained

A

the stain binds to structures

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24
Q

what is immunostaining

A

when labelled antibodies are added to a sample
making specific proteins visible

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25
Q

what is magnification

A

how much bigger the image is than the object

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26
Q

what is resolution

A

how far apart two points can be before they are seen as one

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27
Q

outline the process of using a light microscope

A

shine ray of light onto specimen
different structures absorb different amounts + wavelengths of light
the reflected light is then transmitted to the observer

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28
Q

outline the process of using a transmission electron microscope

A

pass a beam of electrons through specimen
more dense structures appear darker as they absorb more electrons

29
Q

outline the process of using a scanning electron microscope

A

focus a beam of electrons onto specimens surface
reflected electrons hit collecting device
and are amplifies to produce a 3D image

30
Q

outline the limitations of electron microscopes

A

it is expensive

the specimen must be in a vacuum
therefore dead

produces black + white images

31
Q

how are viruses classified

A

by their

shape + structure (enveloped vs non-enveloped)

and

type of nucleic acid (RNA vs DNA and single stranded vs double stranded)

32
Q

give an example of a DNA virus

A

lambda page

33
Q

give examples and features of RNA viruses

A

tobacco mosaic
- non-enveloped
- positive ssRNA
meaning it can be directly translated into proteins

ebola
- enveloped
- negative ssRNA
meaning it must to be transcribed before it can be translated

34
Q

give an example of a RNA retrovirus

A

HIV

35
Q

outline the lysogenic cycle

A
  1. non-virulent virus injects nucleic acid into host cell
  2. viral DNA is replicated when host cell divides
  3. virus produces repressor proteins to inhibit transcription
  4. latent virus enters lytic pathway when host cell is damaged or immune system is weak

(this is mostly done by phages infecting bacteria)

36
Q

outline the lytic cycle

A
  1. virulent virus injects nucleic acid into host cell
  2. viral DNA replicated immediately + independently of the host cells DNA
  3. cell matures + bursts
  4. large numbers of virus released
37
Q

why are viruses classified as non-living

A

they cannot reproduce without a host

38
Q

how do antiviral drugs work

A

drug must interfere with a process in viral life cycle e.g. reverse transcription (RNA->DNA) in HIV you can have an enzyme inhibitor. A drug could also be a cytokine that increases immune response (e.g. interferon)
A drug may stop viral DNA polymerase working (e.g. anti-herpes drug)

39
Q

how do antiviral drugs inhibit viral replication

A

they do this by

  1. targeting viral antigens
    preventing entry into host cell
  2. targeting viral enzymes
    preventing DNA replication + assembly of vision
    e.g. reverse transcriptase inhibitor for HIV
40
Q

list 3 ethical problems associated with the use of untested drugs during epidemics

A

who to treat first

chance of unanticipated side effects

severely ill patients cannot give informed consent

41
Q

name the stages in the cell cycle

A

interphase, mitosis + cytokinesis

42
Q

define mitosis

A

process by which a cell divides into 2 identical daughter cells

43
Q

what is the significance of mitosis

A

growth and repair

and

asexual reproduction

44
Q

outline the stages in interphase

A

G1-
cell synthesises proteins for replication

S phase-
DNA replicates

G2-
organelles divide

45
Q

outline the stages of mitosis

A

prophase
metaphase
anaphase
telophase

46
Q

outline prophase

A

chromosomes condense
spindle fibres form
and
nuclear envelope breaks down

47
Q

outline metaphase

A

chromosomes line up along the equator in a single file line
and
spindle fibres attach at the centromere

48
Q

outline anaphase

A

sister chromatids move to opposite poles
and
centromeres divide

49
Q

outline telophase

A

chromosomes decondense
spindle fibres break down
and
nuclear envelope reforms

50
Q

outline cytokinesis

A

cytoplasm divides
and
parent cell becomes 2 identical daughter cells

51
Q

define meiosis

A

process by which a cell divides into 4 genetically different haploid cells

52
Q

outline meiosis 1

A

prophase 1- same as mitosis
**+ crossing over **of non-sister chromatids -> making recombinant alleles -> with new allele combinations

metaphase I - same as mitosis except homologous pairs of chromosomes instead line up along the equator

anaphase I - same as mitosis except homologous pairs of chromosomes instead move to the poles
+ independent assortment- which way the paternal and maternal chromosomes will be pulled is random

telophase 1- same as mitosis…

results in 2 haploid cells

53
Q

outline meiosis 2

A

all the same as mitosis

prophase 2- same as mitosis
metaphase 2- same as mitosis (single-file)
anaphase 2- same as mitosis (chromatids separate)
telophase 2- same as mitosis

results in 4 genetically different daughter cells (after cytokinesis)

54
Q

how does meiosis bring about genetic variation

A
  • crossing over during prophase 1
  • independent assortment of homologous chromosomes + sister chromatids

resulting in new combinations of alleles in gametes

55
Q

what is a chromosome mutation e.g. translocation

A

when a chromosome is changed on a large scale rather than just at 1 place

so much DNA is lost/gained on a chromosome that it can often be observed with a microscope

e.g. translocation- when part of a chromosome jumps onto another chromosome

56
Q

what is non-disjunction

A

when chromosomes fail to separate correctly + gametes have

1 extra chromosome (polysomy)
e.g. downs syndrome

or

1 missing chromosomes (monosomy) e.g. turners syndrome

57
Q

what are the types of gametogenesis

A

oogenesis + spermatogenesis

58
Q

outline the process of oogenesis

A

diploid primordial gremlin cell
mitosis
oogonia
growth period
primary oocytes

first meiotic division (separating chromosomes)
1 haploid secondary oocyte + 1 polar body

second meiotic division (separating chromatids)
secondary oocyte -> haploid ootid + polar body
polar body -> divides into 2

= ootid + 3 polar bodies (degenerate as ootid develops)

ootid differentiates = ovum

59
Q

outline the process of spermatogenesis

A

1 diploid primordial germline cell
mitosis
2 diploid spermatogonia
loads of mitosis
many diploid primary spermatocytes

each primary spermatocyte
first meiotic division (separating homologous chromosomes)
2 haploid secondary spermatocytes

second meiotic division (separating chromatids)
4 haploid spermatids

spermatids differentiate to gain
- flagellum
- acrosome
- many mitochondria

60
Q

what is the importance of mitosis in spermatogenesis

A

to keep on making more spermatogonia
in order to make more spermatocytes forever

61
Q

outline the process of fertilisation

A
  • enzymes in acrosome of sperm head digest zone pellucida
  • sperm head fuses with the ovums cell membrane -> allowing sperm nucleus to enter
  • cortical granules from ovum are released via exocytosis -> cortical reaction -> causing the zona pellucida to harden -> preventing polyspermy
  • nuclei fuse -> forming a diploid zygote
62
Q

outline the formation of a blastocyst

A

zygote -> several mitotic divisions
-> embryo (2 or more cells)
-> morula (solid ball of identical cells -> which are totipotent)

further divisions, differentiation + cavity formation
-> blastocyst (pluripotent)

63
Q

describe the structure of a blastocyst

A

fluid filled cavity
inner cell mass -> develops into foetus
outer layer -> develops into placenta

64
Q

what and where are the plant gametes found

A

pollen grains in anther

and

embryo sac in ovule

65
Q

how are the male gametes in plants formed

A

diploid microspore cell
meiosis
4x haploid microspores

mitosis
they mature into 4x pollen grains (2x haploid nuclei each)

66
Q

how are the female gametes in plants formed

A

diploid megaspore mother cell
meiosis
1x haploid megaspore + 3x polar bodies (these degenerate then are reabsorbed)

3x mitotic divisions + differentiation
1x megaspore (made up of 8x haploid nuclei- of which 2 are polar nuclei + 1 is the female gamete)

67
Q

how do male nuclei reach the embryo sac

A
  1. pollen grain germinates on stigma
  2. mitosis of generative nucleus -> produces 2x male gametes -> which will enter the embryo sac
  3. enzymes digest the surrounding tissue -> which will allow the tube to grow + provides nutrients -> enabling the pollen tube to grow down the style -> then through micropyle -> into the embryo sac
68
Q

outline the process of double fertilisation

A
69
Q

what sucrose conc do pollen tubes grow best in

A

near isotonic -> as its the same as conc as inside -> preventing osmotic damage

bio (4 decks)

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