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A level Biology- KE > Module 2- Cell Division > Flashcards

Module 2- Cell Division Flashcards

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1
Q

what takes place during G1 phase?

A

cellular components apart from chromosomes are duplicated,, cell increases in size

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2
Q

what takes place during G2 phase?

A

second growth phase,, cell continues to increase in size,, energy stores increased,, duplicated DNA checked for errors

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3
Q

what takes place during S phase?

A

synthesis phase,, DNA replicated in nucleus

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4
Q

what takes place during prophase (mitosis)?

A

-chromosomes condense becoming shorter and fatter
-nuclear envelope disintegrates
-centrioles move to opposite poles of cell to form spindle fibres

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5
Q

what takes place during metaphase (mitosis)?

A

chromosomes move to metaphase plate and attach to the spindle fibres by their centromeres

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6
Q

what takes place during anaphase (mitosis)?

A

-centromere divides separating sister chromatids
-spindle fibres shorten pulling chromatids to opposite poles of the cell by their centromere

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7
Q

what takes place during telophase (mitosis)?

A

-chromatids reach opposite poles
-two new sets of chromosomes assemble and nuclear envelope reforms around them
-chromosomes uncoil
-cytokinesis begins

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8
Q

what takes place during cytokinesis?

A

cytoplasm divides and two cells are produced,, begins during telophase

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9
Q

what is a totipotent stem cell?

A

-can differentiate into any cell including extra-embryonic tissues e.g. placenta

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10
Q

what is multipotent stem cell?

A

-can only form a range of cells within a certain type of tissue

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11
Q

what is a pluripotent stem cell?

A

-can form all tissue types but not whole organisms
-origin of different types of tissue within an organism

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12
Q

what are the potential uses of stem cells in developmental biology?

A

-can be grown into different tissues
to test how effective new medicinal
drugs are and test for side effects/toxicity of them
-studied to see how they develop into different cell types

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13
Q

what happens during crossing over?

A

chromosomes entangle at the chiasmata resulting in exchange of DNA when they break off and re join during anaphase 1

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14
Q

what happens during independent assortment?

A

the position of the homologous pair on metaphase plate is random ∴ different combos of alleles face poles leading to genetic variation

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15
Q

how is a erythrocyte specialized for its function?

A

flattened biconcave shape=increases SA:V maximizing amount of oxygen being transported
no nuclei+not many organelles= more space for haemoglobin
flexible=squeeze through narrow capillaries

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16
Q

how is a neutrophil specialized for its function?

A

-granular cytoplasm containing many lysosomes (containing hydrolytic enzymes) to attack pathogens
-multilobed nucleus=flexibility=can squeeze through small gaps to get to the site of infections + change shape to engulf (phagocytosis)

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17
Q

how are squamous epithelial cells specialized for their function?

A

-very thin flattened shape (only one cell thick) providing short diffusion distance for gases e.g. O2 CO2 in alveoli

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18
Q

how are ciliated epithelial cells specialized for their function?

A

-cells have hair like structures which move in a rhythm to waft mucus containing trapped pathogens away from lungs to the throat///to move egg in fallopian tubes to the uterus

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19
Q

how are sperm cells specialized for their function?

A

-acrosome contains digestive enzymes which are released to digest the protective layers on the ovum allowing to fertilize
-flagellum tail to enable mobility to swim to egg
-lots of mitochondria to supply energy needed to swim

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20
Q

how are guard cells specialized for their function?

A

-cell wall is thicker on one side causes, cell to bend / open stomata

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21
Q

how are palisade cells specialized for their function?

A

-rectangular box shape so can be closely packed to form continuous layer
-thin cell walls to increase rate of diffusion of CO2
-large vacuole to maintain turgor pressure

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22
Q

how are root hair cells specialized for their function?

A

root hairs increase SA of cell maximizing water+mineral uptake from soil

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23
Q

what are stem cells?

A

renewing source of undifferentiated cells (unspecialized)

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24
Q

what happens at prophase I?

A

same as prophase in mitosis ++++

-homologous chromosomes pair up to form bivalents
-crossing over occurs

25
Q

what happens at prophase II?

A

-chromosomes that consist of two chromatids condense and become visible again
-nuclear envelope breaks down
-spindle formation begins

26
Q

what happens at metaphase I?

A

same as metaphase in mitosis +++

-homologous pairs line up on the metaphase plate
-independent assortment

27
Q

what happens at metaphase II?

A

-individual chromatids assemble on metaphase plate
-due to crossing over the chromatids are no longer identical so independent assortment occurs again

28
Q

what happens at anaphase I?

A

-homologous chromosomes are pulled to opposite poles of the cell together
-sections of DNA on sister chromatids break off+re-join resulting in exchange of DNA forming recombinant chromatids

29
Q

what happens at anaphase II?

A

same as anaphase of mitosis

30
Q

what happens at telophase I?

A

-chromatids reach opposite poles
-two new sets of chromosomes assemble and nuclear envelope reforms around them
-chromosomes uncoil
-cytokinesis begins

(same as mitosis)

31
Q

what happens at telophase II?

A

-chromatids reach opposite poles
-two new sets of chromosomes assemble and nuclear envelope reforms around them
-chromosomes uncoil
-cytokinesis begins

(same as mitosis)

32
Q

what happens in mitosis?

A

the nucleus divides

33
Q

what is the product of the cell cycle?

A

two genetically identical daughter cells

34
Q

what does the G1 checkpoint check for?

A

DNA damage, cell size, nutrients

35
Q

what does the G2 checkpoint check for?

A

correct DNA replication + DNA damage

36
Q

what does the metaphase checkpoint check for?

A

if all chromosomes are attached to spindle

37
Q

when do the checkpoints occur?

A

at the end of their phases

38
Q

what happens if the G1 checkpoint fails?

A

cell enters G0

39
Q

what happens if the G1 checkpoint is passed?

A

cell enters S phase for DNA synthesis

40
Q

what happens if the G2 checkpoint is passed?

A

mitosis begins

41
Q

what is mitosis needed for?

A

-asexual reproduction
-growth and repair of tissues
-production of new stem cells

42
Q

what is meiosis needed for?

A

-production of haploid cells
-genetic variation by independent assortment and crossing over

43
Q

what are the potential uses of stem cells in repair of damaged tissues?

A

produce new skin for burns on the body

44
Q

what are the potential uses of stem cells for neurological?

A

stem cells can be transplanted to areas where needed in order to produce lacked cells causing the disease

45
Q

what are the ethical issues surrounding stem cell use?

A

-embryonic stem cells obtained from embryo and then discarded (debate on when life begins)

46
Q

what are homologous chromosomes?

A

matching pair of chromosomes, one inherited from each parent which have the same genes but but different alleles of the gene

47
Q

what stage does crossing over occur?

A

prophase 1

48
Q

what stage does independent assortment occur?

A

metaphase 1 and 2

49
Q

what is a tissue?

A

made up if a collection of differentiated cells that have specialized function,, each tissue is adapted for a particular function within an organism

50
Q

what is an organ?

A

collection of tissues adapted to perform a particular function within an organism

51
Q

what is an organ system?

A

multiple organs working together to carry out a major function in the body e.g. digestive system

52
Q

what are the four main types of tissue in an organism?

A

xylem, phloem, muscle, cartilage, squamous and ciliated epithelia

53
Q

what is cartilage?

A

firm flexible connective tissue

54
Q

what is the potency of a stem cell?

A

its ability to differentiate

55
Q

where and how are xylem and phloem produced?

A

produced in meritem by differentiation

56
Q

where is meristematic tissue found?

A

-wherever growth is occurring e.g. tips of roots and shoots
-vascular cambium (area sandwiched between phloem and xylem)–can differentiate into the different cells present in xylem + phloem tissues

57
Q

where are erythrocytes and neutrophils both derived from?

A

bone marrow

58
Q
A

A level Biology- KE (19 decks)

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