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A A A Level Biology > cell division cell diversity > Flashcards

cell division cell diversity Flashcards

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1
Q

what processes happen during interphase

A
  • DNA replicated + checked for errors
  • protein synthesis occurs in cytoplasm
  • mitochondria numbers increase and chloroplasts
  • normal metabolic processes occur
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2
Q

what happens during G1 of interphase

A

first growth phase

  • organelles made and replicated
  • cell increases in size
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3
Q

what happens during S phase of interphase

A

DNA replicated in nucleus

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4
Q

what happens during G2 phase of interphase

A

cell increases in size
energy stores increase
duplicated DNA checked for errors

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5
Q

what does the G1 Checkpoint do

A

checks cell size , nutrients
growth factors and if any DNA damage

if doesnt pass then goes to G0

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6
Q

what does the G2 checkpoint do

A

end of G2 checks cell size again
DNA checked again
and checks DNA replication went accurately

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7
Q

what is the spindle assembly checkpoint

A

aka metaphase checkpoint
where all chromosomes should be attached to spindles and have aligned
Mitosis cant proceed if this not done

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8
Q

what happens during prophase of mitosis

A

chromatin coils and condenses to form CHROMOSOMES
>nucleolus breaks down
>microtubules form spindle fibres
>centrioles migrate to poles
>chromosomes begin to be pulled to centre of cell by spindle fibres

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9
Q

what happens during metaphase

A

> chromosomes are moved by spindle fibres to centre of cell on metaphase plate

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10
Q

what happens during anaphase of mitosis

A

centromeres holding pairs of chromatids in each centromere divide
and are pulled to poles as spindle fibres shorten and contract

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11
Q

what happens during telophase of mitosis

A

chromatids have reached poles and are now called chromosomes
the 2 new sets of chromosomes assemble at poles
>nuclear envelope reforms around them
>chromosomes uncoil and nucleolus is formed

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12
Q

what happens during cytokinesis in animal cells

A
  • cleavage furrow forms in middle of the cell

- cell membrane pulled inwards by cytoskeleton until it can fuse in middle forming 2 cells

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13
Q

what happens in cytokinesis in plant cells

A

cant form cleavage furrow due to cell walls
-vesicles from Golgi apparatus assemble in saem place as where the metaphase plate was formed

these vesicles fuse togteher with cell surface membrane dividing the cell in two
(if cell wall was formed before daughter cells formed they would undergo osmotic lysis from surrounding water)

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14
Q

what happens during prophase 1 of meiosis

A

chromosomes condense, nuclear envelope disappears and nucleolus disappears
>spindle fibre formation begins

homologous chromosomes pair up to form bivalents
»»chromosomes brought together entangle causing CROSSING OVER to occur

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15
Q

what happens during metaphase 1 of meiosis

A

same as mitosis BUT HOMOLOGUS CHROMOSOMES line up on metaphase plate not individual chromosomes
>this is random orientation so maternal and patternal can face either pole causing independent assortment

genetic variation

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16
Q

what happens during anaphase 1 of meiosis

A

DIFFERENT from mitosis

homologous CHROMOSOMES are pulled to opposite poles but chromatids stay joined
>sections of DNA on sister chromatids (which were entangled in crossing over) break off and rejoin which exchanges DNA at points called chiasma/ta
»>forms RECOMBINANT CHROMATIDS and genes are exchanged between sister chromatids + GENETIC VARIATION

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17
Q

what happens during telophase 1 of meosis

A

same as mitosis

chromosomes assemble at each pole and nuclear membrane reforms and chromosomes uncoil!!

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18
Q

what happens in prophase 2 of meiosis

A

chromosomes which still consist of 2 chromatids condense and become visible again.
Nuclear envelope breaks down and spindle fibres form

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19
Q

what happens in metaphase 2 of meiosis

A

different to 1 in that INDIVIDUAL chromosomes assemble on metaphase plate not homologous

> independent assortment again more genetic variation

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20
Q

what happens in anaphase 2 of meiosis

A

unlike anaphase 1 , results in CHROMATIDS of individual chromosomes being pulled to opposite poles after division of the centromere.

results in separation of sister chromatids

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21
Q

what happens in telophase 2 of meiosis

A

> chromatids assemble at poles (same as mitosis)
they uncoil and form chromatin again and nuclear envelope reforms and nucleolus becomes visible.

cytokinesis occurs after forming 4 daughter cells which are haploid due to reduction division and are all genetically different due to crossing over and independent assortment

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22
Q

what are homologous chromosomes

A

A couple of homologous chromosomes are a set of one maternal and one paternal chromosome that pair up with each other

alleles at same locus

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23
Q

where is a plant can growth occur

A

cambium

meristematic tissue

24
Q

what does the cambium do

A

cells differentiate into xylem and phloem vascular bundles

25
Q

how does reproduction occur in fungi

A

like yeast
asexually by budding
cells swell on one side and bulge
nucleus moves into bulge and evntually pinches off and cell wall forms creating separate cell

26
Q

what is the importance of mitosis

A
  • growth of organism
  • replacement + repair of tissues
  • asexual reproduction
27
Q

how do prokaryotes (eg bacteria) reproduce

A

binary fission

28
Q

how is meiosis significant in life cycles

A

produces 4 haploid cells all genetically different due to crossing over and independent assortment that occurs in meiosis

29
Q

what is independent assortment

A

Mendel’s law of independent assortment states that the alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene.

30
Q

how are erythrocytes specialised

A

> flattened biconcave shape which increases their surface area to volume ratio
this is essential for them carrying oxygen around the body
no organelles or nucleus so more space
flexible to fit through narrow capillaries

31
Q

how are neutrophils specialised

A

type of white blood cell used in immune syst.
> multilobed nucleus which makes easier to fit through small gaps to the site of infections
> granular cytoplasm contains lysosomes which contain enzymes used to attack pathogens

32
Q

how are sperm cells specialised

A

> function is to deliver genetic information to the female gamete
tail or flagellum for movement and have many mitochondria to supply the energy needed to swim
acrosome head contains digestive enzymes which digest protective layers around the ovum and allow sperm to penetrate

33
Q

how are palisade cells specialised

A

> present in mesophyll and contain CHLOROPLASTS which absorb light for photosynthesis
box shaped to pack closely and form a continuous layer
thin cell walls decreasing diffusion distance for CO2
large vacuole to maintain turgor pressure
chloroplasts can move within cytoplasm to absorb more light

34
Q

how are root hair cells specialised

A

> in roots near growing tips
long extensions called root hairs which increase surface area of cell
maximises water and mineral uptake

35
Q

how are guard cells specialised

A

pairs are found on surfaces of leaves to form small openings called stomata
>CO2 enters here for photosynthesis
>when lose water become less swollen and due to osmotic forces they change shape and stoma closes to prevent further water loss from plant
>cell wall thicker on one side so cell does not change shape symmetrically as volume changes

36
Q

what are the 4 types of animal tissue

A

nervous tissue- to support transmission of elec impulse
epithelial tissue- cover body surfaces int. and external
muscle tissue- adapted to contract
connective tissue- adapt either to hold other tissues together or act as a transport medium

37
Q

how is squamous epithelium tissue specialised

A

tissue type
flat + thin squammous epithelial cells which are very thin due to the squat or flat cells that make it up because its only one cell thick
>present when rapid diffusion needed across a membrane
>forms lining of lungs, and allows rapid diffusion of oxygen into the blood

38
Q

how is cilliated epithelium tissue specialised

A

> hair like structures on cilliated epithelial cells called cilia which move in rhythmic manner
line trachea to waft mucus away from lungs
goblet cells also present in tissue to release mucus to trap unwanted particles present in the air to prevent particles reaching alveoli once in lungs

39
Q

how is cartilage tissue specialised

A

> ear nose ends of and between bones
contains fibres of collagen and elastin proteins
firm flexible and connective tissue made of chondrocyte cells embedded in an extracellular matrix
prevents bones rubbing
fish may have whole skeletons made of cartilage not bone

40
Q

how is muscle tissue specialised

A

need to be able to shorten in length and contract to move bones
>there are different types of muscle fibres: skeletal fibres which are attached to the bone contain myofibrils which contain contractile proteins

41
Q

what are the different types of tissue in plants

A

> epidermis tissue adapted to cover plant surfaces

>vascular tissue adapted for the transport of water and nutrients

42
Q

how is the epidermis tissue specialised

A

> single layer of closely packed cells covering plant surfaces
usually covered by waxy waterproof layer to reduce water loss
stomata formed by a pair of guard cells can open and close and are present in epidermis which allow gas exchange

43
Q

how is xylem tissue specialised

A

transport water and minerals through plant
> composed of elongated dead cells strengthened with lignin (waterproof)
>no end walls to cells to allow water through

44
Q

how is phloem tissue specialised

A

> another vascular tissue in plants responsible for transport of organic nutrients like sucrose from leaves and stems where it is made by photosynthesis
composed of sieve tube cells separated by perforated walls called sieve plates

45
Q

what are the 3 organ systems you need to know

A

> digestive system to removed indigestible material
cardiovascular system
gaseous exchange system

46
Q

what are stem cells

A

undifferentiated cells which orgionate from mitosis or meiosis which arent adapted to any function and can differentiate into any times of cell

47
Q

what happens when stem cells are specilised

which cell phase do they enter

A

G0 phase they lose the ability to divide

48
Q

why does the activity of stem cells need controlling

A
  • if they dont divide fast enough tissues arent efficiently replaced which can lead to aging
  • too much uncontrolled division can cause tumors and cancer
49
Q

what are the different types of potency of stem cells

A

Totipotent- differentiate into any type of cell (usually in fertilised egg or zygote) evntually form the whole organism

pluripotent- stem can form all tissue types but not whole organism. present in early embryo and are the origin of different tissue types in the organism

multipotent- can only form a range of cell within a certain type of tissue
haematopoetic stem cells in bone marrow are multipotent as makes various types of blood cells

50
Q

how are erythrocytes and neutrophils produced from stem cells

A

in bone marrow by multipotent SCells called haematopoetic cells
>due to lack of organelles and nucleus rbcells have short life span of 120 days ish so need constant replacement
>neutrophils have even shorter lifespan of about 6 hours and are produced more of when infection arises

51
Q

what are the sources of plant stem cells

A

meristematic tissue
sandwiched between phloem and xylem called the vascular cambium and also found in tips of roots and shoots

pluripotent nature through plant life so vascular tissue grows with plant

52
Q

how could stem cells be used to repair damaged tissues

A

treating patients with heart disease

53
Q

how could stem cells be used to treat parkinsons

A

caused by death of dopamine cells in brain

54
Q

how could stem cells be used to treat alzheimers

A

brain cells destroyed due to build up of abnormal proteins

55
Q

how are stem cells used in developmental biology

A

this is the study of the changes that occur as multicellular orgs grow and develop from single cell such as a fertilised egg

A A A Level Biology (22 decks)

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