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Biology A1 OCR A > Cell Division > Flashcards

Cell Division Flashcards

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1
Q

describe what happens at each stage of the cell cycle

A

GAP PHASE 1- cell grows, new organelles and proteins are made
G1 CHECKPOINT- the cell checks that the chemicals needed for replication are present and for any damage to the DNA before entering s phase.
G0 PHASE-cells differentiate,become at rest (senescence) or die(if DNA is damaged)
SYNTHESIS- cell replicates DNA, ready to divide by mitosis
GAP PHASE 2- cell keeps growing and proteins needed for cell division are made
G2 CHECKPOINT- without any damage the cell can enter mitosis
M PHASE- mitosis and cytokinesis followed by metaphase checkpoint

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2
Q

what is the structure of chromosomes in mitosis?

A

beginning: two strands joined in centre by centromere
the separate strands are called chromatids

Interphase until end: two strands on the same chromosome are called sister chromatids
end:when mitosis is over chromatids ends up as one strand chromosome

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3
Q

describe each stage of mitosis (PMAT)

A

INTERPHASE- cell is preparing to divide
DNA replicates

cell growth
ATP production is increased
PROPHASE- chromosomes condense and become visible
nuclear envelope breakdown
nucleolus breaks up and disappears
centrioles migrate to opposite poles
mitotic spindle fibres start to form

METAPHASE- spindle fibres attach onto the centromeres
chromosomes are organised across the centre of cell (metaphase plate)

ANAPHASE- spindle fibres contract and pull the sister chromatids apart
cell starts to elongate

TELOPHASE- the chromosomes are no longer visible
nuclear envelope and nucleolus reformes

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4
Q

what happens during cytokinesis?

A

cytoplasm divides
in animal cell: cleavage furrow forms to divide the cell membrane

in plant cell: the vesicles start to grow until it splits the cell into two
two daughter cells that are genetically identical to original cell
cytokinesis begins in anaphase & ends in telophase

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5
Q

what is the structure of chromosomes in mitosis?

A

beginning: two strands joined in centre by centromere
the separate strands are called chromatids

Interphase until end: two strands on the same chromosome are called sister chromatids
end:when mitosis is over chromatids ends up as one strand chromosome

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6
Q

describe each stage of mitosis (PMAT)

A

INTERPHASE- cell is preparing to divide
DNA replicates

cell growth
ATP production is increased
PROPHASE- chromosomes condense and become visible
nuclear envelope breakdown
nucleolus breaks up and disappears
centrioles migrate to opposite poles
mitotic spindle fibres start to form
METAPHASE- spindle fibres attach onto the centromeres
chromosomes are organised across the centre of cell (metaphase plate)
ANAPHASE- spindle fibres contract and pull the sister chromatids apart
cell starts to elongate
TELOPHASE- the chromosomes are no longer visible
nuclear envelope and nucleolus reformes

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7
Q

what happens during cytokinesis?

A

cytoplasm divides
in animal cell: cleavage furrow forms to divide the cell membrane

in plant cell: the vesicles start to grow until it splits the cell into two
two daughter cells that are genetically identical to original cell
cytokinesis begins in anaphase & ends in telophase

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8
Q

what is meiosis and where does it take place?

A

allows the production of genetically distinct haploid daughter cells from a diploid parent cell
it occurs in the gametes where two haploid gametes fuse to form one diploid cell

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9
Q

how is meiosis different to mitosis?

A

mitosis results in 2 identical daughter cells, whereas meiosis results in 4 sex cells

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10
Q

define diploid

A

a cell containing two complete sets of chromosomes, one from each parent

46 chromosomes,23 pairs

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11
Q

define haploid

A

quality of a cell organism having a single set of chromosomes
organisms that reproduce asexually are haploid

23 chromosomes

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12
Q

define allele

A

alternative forms of a gene that arise by mutation and are found at the same place on a chromosome

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13
Q

define homologous chromosome

A

chromosome pairs where one is paternal and the other is maternal,They are approximately the same length, centromere position and banding pattern for genes with the same corresponding loci.

They pair up in meiosis/form bivalents

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14
Q

define chromatid

A

one-half of a duplicated chromosome

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15
Q

define sister chromatids

A

identical copies of the same chromosome formed by DNA replication
attached to each other by a centromere

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16
Q

describe each stage of meiosis

A

PROPHASE 1- chromosomes condense
~begin to pair up
~nuclear envelope breakdown
~centrioles move to opposite poles
~homologous chromosomes pair up form bivalents-crossing over occurs
METAPHASE 1- pairs of homologous chromosomes line up at the centre
independent assortment occurs
ANAPHASE 1- spindle fibres contract and homologous chromosomes are pulled apart,chromatids stay joined together
~entangled sections during crossing over break off & rejoin @ point called chiasmata. Chromatids now are recombinant
TELOPHASE 1- nuclear envelope reforms
CYTOKINESIS- two haploid cells are produced
METAPHASE 2- chromosomes line up across the centre
more independent assortment
ANAPHASE 2- spindle fibres contract
sister chromatids pull apart
centromeres splits
TELOPHASE 2- nuclear envelope reforms
CYTOKINESIS- four haploid daughter cells are produced

17
Q

name three things in meiosis that leads to increased variation

A

recombination of parental genes when haploid cells fuse during fertilisation
independent assortment of chromosomes during metaphase 1&2

crossing over occurs during meiosis 1 resulting in chromosomes containing a different combination of alleles

18
Q

what is a tissue?

A

a group of cells that are specialised to work together to carry out a particular function

19
Q

what is a muscle tissue?

A

it’s made up of bundles of elongated cells called muscle fibres
3 different types:

smooth muscle- lining the stomach
cardiac- the heart
skeletal-used to move

20
Q

what is cartilage?

A

type of connective tissue found in joints
shapes and supports ears, nose and windpipe

formed when cells called chondroblasts secrete an extracellular matrix containing protein fibres which they become trapped inside

21
Q

what is xylem tissue?

A

plant tissue with 2 jobs- transports water around the plant and supports the plant
contains a hollow xylem vessel cell (which are dead) and living parenchyma cells

22
Q

what is phloem tissue?

A

transports sugars around the plant
arranged in tubes and is made of sieve cells, companion cells and ordinary plant cells

each sieve cell has end walls with holes in them so that can sap moves through
end walls are called sieve plates

23
Q

what are lungs?

A

animal organ which carry out gas exchange
contain squamous and ciliated epithelium tissue

have elastic connective tissue and vascular tissue

24
Q

what is the leaf?

A

plant organ which carries out gas exchange and photosynthesis
contains palisade and epidermal tissue to prevent water loss from leaf

xylem and phloem tissue in the veins

25
Q

what is an organ system?

A

organs work together to form organ system each system has a particular function

26
Q

How are erythrocytes and neutrophils,sperm, squamous and ciliated epithelium cells cells adapted for their functions

A

RBC:
biconcave shape-large S.A for gas exchange,no nucleus so more space for haemoglobin.
-flexible to squeeze through narrow capillaries

Neutrophils

  • multi-lobed nucleus-easier 2 squeeze through small spaces to reach sight of infection.
  • flexible -engulf foreign pathogen
  • granular cytoplasm contain lysosomes with digestive enzymes 2 break engulfed particle down.

sperm cells:

  • flagellum propels sperm forward to egg cell
  • A lot of mitochondria for energy-movement
  • acrosome contains digestive enzyme 2 break down protective layer of ovum.

ciliated epithelium cells:

  • hair-like structures called cilia/microvilli that move in rhythmic pattern to beat moving particles away.
  • so have many mitochondria for movement
  • contains goblet cells-produce mucus to trap particles

squamous:
-1 cell thick allowing efficient gas exchange in alveoli

27
Q

How are palisade cells,root hair cells and guard cells adapted for their functions

A

palisade cell:

  • contain a lot chloroplasts so they can absorb a lot of sunlight
  • walls are thin,co2 diffuse easily

Guard cells:

  • loss of water,due to osmotic forces guard cells close up, preventing further loss
  • thicker inner wall,thinner outer wall force to bend outwards,opening stomata.

root hair cells:

  • Root hairs- large S.A
  • thin permeable cell wall-entry of water and ions
  • extra mitochondria-ENERGY FOR ACTIVE TRANSPORT
28
Q

How are erythrocytes and neutrophils derived from stem cells

A

erythrocytes and neutrophils are blood cells.So production of them is HEMATOPOIESIS.

29
Q

How are xylem vessels and phloem

sieve tubes produced from meristems

A

meristems found in growth areas-tips and shoots. and vascular cambium.These stem cells differentiate into different types of cells present in xylem and phloem.

So vascular bundle grows as plant grows.These stem cells continue to be pluripotent entire ife.

30
Q

How are stem cells useful for experimental biology

A

experimental biology -the study of changes that occur as multicellular organisms develop from a single cell and where things go wrong.

31
Q

How are stem cells useful for experimental biology

A

experimental biology -the study of changes that occur as multicellular organisms develop from a single cell and where things go wrong.

stem cells differentiating into any cell is useful as scientists can identify steps it takes to become differentiated healthily and where it went wrong of a diseased cell

32
Q

what is cell potency

A

stem cell’s ability to differentiate into different types cells.

33
Q

outline what is meant by totipotent, pluripotent, multipotent

A

totipotent-is when a cell is able to differentiate in any type of cell, which eventual becomes a whole organism.beginning of a zygote/fertilized egg is toti.

pluripotnt- stem cells can form all tissue types but not organims.Present in early embryo

multipotent-only range of cells in certain type tissues
E.G hematopoietic stem cell in bone marrow-different typw blood cells(rbc+ neutrophils)

34
Q

How are stem cells useful for neurological conditions

A

parkinsons- dopamine producing nerve cells dead.SO transplanted stem cells may help regenerate dopamine producing cells

Alzheimer’s- nerve cells in brain dead.Scientists hope to make new nerve cells using stem cells

Biology A1 OCR A (8 decks)

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