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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

Study These Flashcards
A
  • division of the cell / cytoplasm
23
Q

Definition of senescence

24
Q

Definition of apotosin

Study These Flashcards
A

programmed cell death

25
What happens in the cell arrest phase
* check for faulty cells
26
What is classed as a faulty cell
* too small ( cell size ) * old age * differentiation * damaged DNA
27
What is a cyclin
* cell signaling molecule * binds to an enzyme (CDK) they active it by altering the shape of the active site
28
What are the 4 stages of mitosis?
* prophase - prepare * metaphase - middle * anaphase - away * telophase - together
29
What happens during prophase in mitosis
* chromosomes are condensed * chromosomes and sister chromatid joined together by a centromere * spindle fibres form * nuclear envelope breaks down * nucleolus disappears
30
What happens during metaphase in mitosis
* 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
What happens during anaphase in mitosis
* the sister chromatids seperate at the centromere * spindle fibres begin to shorten * sister chromatids are pulled to opposite poles by the spindle fibres
32
What happens during telophase in mitosis
* chromosomes begin to decondense * nuclear envelope begins to reform * spindle fibres break down * new nucleoli form within each nucleus
33
What is the significance of mitosis
1. asexual reproduction 2. repair tissues 3. replacement of cells 4. growth of mutlicellular organisms
34
What happens during prophase 1 in meiosis
* 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
What happens during metaphase 1 in meiosis
* 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
What happens during anaphase 1 in meiosis
* homologous pairs are seperated as the microtubles move the spindle to pull the whole chromosomes to opposite ends * the centromeres don't divide
37
What happens during telophase 1 in meiosis
* spindle fibres breaks down * nuclear envelope forms around the two groups of chromosomes and nucleoli form
38
What happens during cytokensis in meiosis
* division of the cytoplasm * cell organelles are distrubuted evenly * cell surface membrane pinches off and creates a clevage burrow * produces two haploid cells
39
What happens during prophase 2 in meiosis
* nuclear envelope is broken down and chromosomes condense * a spindle forms
40
What happens during metaphase 2 in meiosis
* chromosomes line up along the equator
41
What happens during anaphase 2 in meiosis
* chromatids are pulled to opposite poles * creates 4 groups of chromsomes that have half the amount from parent cells
42
What happens during telophase 2 in meiosis
* nuclear membranes form around each group of chromosomes
43
What is the signifcance of meiosis
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
Cytokinesis stage in a plant
* 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
Cytokinesis stage in an animal
* organelles distribute evenly around the nucleus * centre of the cell pinches and forms a clevage furrow * pulled inwards by the cytoskeleton
46
46
How is genetic variation achieved in meiosis
1. Crossing over (chiasmata) = prophase 1 2. Independent assortment of homologous chromosomes = metaphase 1 3. Independent assortment of chromatids = metaphase 2
47
Define totipotency
can divide into any cell type found in the embryo and extra-embroyonic cells (placenta)
48
Define pluripotency
can divide into any cell type found in the embryo
49
Define multipotency
can divide into a limited range of cell types
50
What can cells in the bone marrow differentiate into
* erythrocytes * monocytes * neutrophils * lymphocytes
51
Benefits of using stem cells
* treat a wide variety of diseases * organs developed from own stem cells reduces risk of rejection * already successfully using adult stem cells
52
Issues with using stem cells
* 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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