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Biology > 2.6 cell division > Flashcards

2.6 cell division Flashcards

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1
Q

Definition of tissue

A

a collection of differentiated cells that together have a specialised function in an organism

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2
Q

Definition of organ

A

forms a distinct structural and functional unit within an organism that is made from more than one tissue

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3
Q

Definition of an organ system

A

a collection of organs with a particular function

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4
Q

Structure to function of a erythrocytes(red blood cell)

A
  • flattened, bioconcave shape = increasse surface area for transporting oxygen
  • no nucleus = more space for haemoglobin
  • flexible = squeeze through narrow capillaries
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5
Q

Structure to function of neutrophils

A
  • multi-lobed nucleus = squeeze through small gaps to access sites of infection
  • granular cytoplasm = full of lysosomes for the breakdown of englufed pathogens
  • essential role in the immune system
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6
Q

Structure to function of a spermatoza

A
  • flagellum = provides motility to swim to the egg
  • many mitochondria = provide ATP for swimming
  • acrosome on the head = contains digestive enzymes to penetrate the outside of the egg during fertilisation
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7
Q

Structure to function of a palaside cell

A
  • many chloroplasts = absorb light in photosynthesis
  • retangular shape = continous layer for maximal light absorption
  • thin cell walls = reduce diffusion distances of carbon dioxide
  • large vacuole = maintain turgidity
  • found in mesophyll layer of the leaf
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8
Q

Structure to function of root hair cells

A
  • long extensions (root hairs) = increase the surface area for absorption of water and mineral ions from the soil
  • found at the surfaces of the root within the epidermis
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9
Q

Structure to function of a guard cell

A
  • found in pairs on the lower epidermis of the leaves
  • stomato are the site of gaseous exchange in plants
  • inner cell wall thick and rigid = when turgid it changes shape by curving causing the stomata pore to open
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10
Q

Structure to function of a squamous epithelium

A
  • one cell thick = rapid diffusion (eg. alveoli)
  • basement membrane holds the epithelium onto the other tissues
  • ‘pavement epithelial’ flat
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11
Q

Structure to function of a ciliated epithelium

A
  • cilia = move in a synchronised pattern to move materials
  • often associated with glandular tissue that secrete mucus (goblet cells)
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12
Q

Structure to function of a connective tissue (cartilage)

A
  • firm and flexible - made of chondrocyte cells embedded in the extra cellular matrix
  • matrix consists of collagen fibres (strength) and elatin fibres (flexibility)

three forms:
1. hyaline - ends of bones/airways/nose
2. fibrous - vertebrae discs
3. elastic - outer ear

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13
Q

Structure to function of a muscle

A
  • muscle fibres contain contractile proteins called myofilaments = bring about movement

three forms
1. skeletal = joined to bones
2. cardiac = makes up the wall of the heart
3. smooth = makes up the walls on the intestine, blood vessels, airways, uterus, and urinary tracts

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14
Q

Structure to function of epidermis

A
  • made of single layer of closely packed cells = provide protective covering on leaves/ stems/ roots
  • covered in waxy cuticle = prevent infection
  • found with guard cells = gaseous exchange
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15
Q

Function of a vascular tissue - xylem

A

transport tissue that carries water and minerals from the roots to the rest of the plant
* consists of hollow columns of elongated dead cells lined end to end and reinforced with lignin
* lignification strengthens the cell wall and ensures that the xylem vessels do not collapse

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16
Q

What is the cell cycle triggered by

A

cyclins

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17
Q

What does the interphase consist of?

A

G1
S
G2

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18
Q

What happens in the G1 phase

A
  • cell growth of the cell
  • replication of organelles
  • protein synthesis
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19
Q

What happens in the S phase

A
  • DNA replication
  • chromosomes unwound
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20
Q

What happens in the G2 phase

A
  • DNA checked for errors
  • respiration
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21
Q

What happens in the M phase

A
  • formation of the spindle
  • seperation of chromatids
  • supercoiling of chromosomes
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22
Q

What happens in the cytokinesis phase

A
  • division of the cell / cytoplasm
23
Q

Definition of senescence

A

cell aging

24
Q

Definition of apotosin

A

programmed cell death

25
Q

What happens in the cell arrest phase

A
  • check for faulty cells
26
Q

What is classed as a faulty cell

A
  • too small ( cell size )
  • old age
  • differentiation
  • damaged DNA
27
Q

What is a cyclin

A
  • cell signaling molecule
  • binds to an enzyme (CDK) they active it by altering the shape of the active site
28
Q

What are the 4 stages of mitosis?

A
  • prophase - prepare
  • metaphase - middle
  • anaphase - away
  • telophase - together
29
Q

What happens during prophase in mitosis

A
  • chromosomes are condensed
  • chromosomes and sister chromatid joined together by a centromere
  • spindle fibres form
  • nuclear envelope breaks down
  • nucleolus disappears
30
Q

What happens during metaphase in mitosis

A
  • spindle fibres continue to extend from centrosomes
  • chromosomes line up at the equator
  • each sister chromatid is attached to a spindle at opposite poles
31
Q

What happens during anaphase in mitosis

A
  • the sister chromatids seperate at the centromere
  • spindle fibres begin to shorten
  • sister chromatids are pulled to opposite poles by the spindle fibres
32
Q

What happens during telophase in mitosis

A
  • chromosomes begin to decondense
  • nuclear envelope begins to reform
  • spindle fibres break down
  • new nucleoli form within each nucleus
33
Q

What is the significance of mitosis

A
  1. asexual reproduction
  2. repair tissues
  3. replacement of cells
  4. growth of mutlicellular organisms
34
Q

What happens during prophase 1 in meiosis

A
  • chromatids condense
  • sister chromatids are arranged as a homologous pair (bivalent)
  • non-sister chromatids may cross over called chisma
  • spindle is formed
  • nuclear envelope is broken down
35
Q

What happens during metaphase 1 in meiosis

A
  • bivalents line up along the equator of the spindle
  • maternal and paternal chromosomes line up in the middle and independent assortment happens ( a proportion of maternal and paternal will end up on either side of the equator to allow for variation )
36
Q

What happens during anaphase 1 in meiosis

A
  • homologous pairs are seperated as the microtubles move the spindle to pull the whole chromosomes to opposite ends
  • the centromeres don’t divide
37
Q

What happens during telophase 1 in meiosis

A
  • spindle fibres breaks down
  • nuclear envelope forms around the two groups of chromosomes and nucleoli form
38
Q

What happens during cytokensis in meiosis

A
  • division of the cytoplasm
  • cell organelles are distrubuted evenly
  • cell surface membrane pinches off and creates a clevage burrow
  • produces two haploid cells
39
Q

What happens during prophase 2 in meiosis

A
  • nuclear envelope is broken down and chromosomes condense
  • a spindle forms
40
Q

What happens during metaphase 2 in meiosis

A
  • chromosomes line up along the equator
41
Q

What happens during anaphase 2 in meiosis

A
  • chromatids are pulled to opposite poles
  • creates 4 groups of chromsomes that have half the amount from parent cells
42
Q

What happens during telophase 2 in meiosis

A
  • nuclear membranes form around each group of chromosomes
43
Q

What is the signifcance of meiosis

A

Genetic variation and sexual reproduction
* crossing over (chiasmata) - non sister chromatids exchange alleles
* independent assortment - randomly allignment of homologous pairs along the equator of the spindle
* random fusion of gametes - any male gamete can fertilise any female gamete

44
Q

Cytokinesis stage in a plant

A
  • vesicle from golgi body containing lamella and cellulose cell wall chemicals move towards the cell centre
  • vesicles form a cell plate
  • new cell membrane and cell wall and divides the cell
45
Q

Cytokinesis stage in an animal

A
  • organelles distribute evenly around the nucleus
  • centre of the cell pinches and forms a clevage furrow
  • pulled inwards by the cytoskeleton
46
Q
A
46
Q

How is genetic variation achieved in meiosis

A
  1. Crossing over (chiasmata) = prophase 1
  2. Independent assortment of homologous chromosomes = metaphase 1
  3. Independent assortment of chromatids = metaphase 2
47
Q

Define totipotency

A

can divide into any cell type found in the embryo and extra-embroyonic cells (placenta)

48
Q

Define pluripotency

A

can divide into any cell type found in the embryo

49
Q

Define multipotency

A

can divide into a limited range of cell types

50
Q

What can cells in the bone marrow differentiate into

A
  • erythrocytes
  • monocytes
  • neutrophils
  • lymphocytes
51
Q

Benefits of using stem cells

A
  • treat a wide variety of diseases
  • organs developed from own stem cells reduces risk of rejection
  • already successfully using adult stem cells
52
Q

Issues with using stem cells

A
  • ethical issue - killing a baby?
  • expensive to collect embryonic stem cells before birth
  • risk of cultured stem cells getting a mutation
  • cultured stem cells can become infected with a virus
  • low number of cell donors

Biology (12 decks)

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