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Biology > Cell Divison, Cell Diversity And Cell Differentiation > Flashcards

Cell Divison, Cell Diversity And Cell Differentiation Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is interphase?

A

Phase of cell cycle where the cell is not dividing; it is subdivided into growth and synthesis phases

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2
Q

What is mitosis.

A

Type of nuclear division that produces daughter cells genetically identical to each other and to the parent cell

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3
Q

What is cytokinesis?

A

Cytoplasmic division following nuclear division, resulting in two new daughter cells

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4
Q

What are the two main checkpoints?

A

G1/s checkpoint also called restriction point

G2/M checkpoint

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5
Q

What are the purpose of checkpoints?

A

Prevent uncontrolled division that would lead to tumours

Detect and repair damage to DNA

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6
Q

M phase

A

A checkpoint chemical triggers condensation of chromatin

Halfway through the cycle, metaphase checkpoint ensures cell is ready to complete mitosis

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7
Q

Events during M phase

A

Cell growth stops
Nuclear division consisting of stages: prophase, metaphase, anaphase and telophase
Cytokinesis

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8
Q

G0 phase

A

Resting phase triggered during early g1 at the restriction point, by a checkpoint chemical
Some cells don’t have this

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9
Q

Events during g0 phase

A

Cells undergo apoptosis, differentiation or senescence

Some types of cells remain in this phase for a very long time

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10
Q

G1 phase (also called growth phase)

A

G1 checkpoint control mechanism ensures that the cell is ready to enter the s phase and begin DNA synthesis

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11
Q

Events in G1

A 
Cells grow and increase in size 
Transcription 
Organelles duplicate 
Biosynthesis 
P53 gene helps control this phase
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12
Q

S phase of interphase

A

Because chromosomes are unwound and DNA is diffused, every molecule of DNA is replicated
Housekeeping genes which are active in all cells are duplicated first
Normally inactive genes are duplicated last

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13
Q

Events in s phase

A

Once entering this phase, cell is commited to completing cell cycle
DNA replicates
When all chromosomes are duplicated, each one consists of a pair of identical sister chromatids
Phase is rapid and exposed DNA are more susceptible to mutagenic agents. Reduces the chance of spontaneous mutation

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14
Q

G2 phase of interphase

A

Chemicals ensure the cell is ready for mitosis by stimulating proteins that will be involved in making chromosomes condense and in formation of spindles

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15
Q

G2 events

A

Cells grow

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16
Q

What are chromatids?

A

Replicates of chromosomes

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17
Q

What is cytokinesis?

A

Division of the cytoplasm of a cell following mitosis

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18
Q

What is mitosis?

A

Type of nuclear division that maintains the chromosome number; each new daughter cell contains the same genetic information as the parent cell. Genetically identical

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19
Q

What is asexual reproduction and where does it occur?

A

Single celled protoctists such as amoeba divide by mitosis
Some plants produce new plantlets on the end of stolons
Fungi use mitosis
Some female sharks without male produces offspring that is genetically identical
Aphids may produce eggs that do not need fertilising

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20
Q

How do multicellular organisms grow?

A

All multicellular organisms grow by producing cells that are genetically identical to each other and to the parent cell from which they arose by mitosis

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21
Q

How do tissues repair?

A

Wounds heal when growth factors, secreted by platelets and macrophages and damages cells of the blood vessel walls, stimulate the proliferation of endothelial and smooth muscle cells to repair damaged blood vessels

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22
Q

Events during prophase?

A

Chromosomes shorten and thicken as DNA is supercoiled
Nuclear envelope breaks down
Centriole in animal cell divides and two new daughter centrioles move to opposite poles
Cytoskeleton protein threads form spindles between centrioles
(In plants tubulin threads form from cytoplasm)

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23
Q

Events during metaphase

A

Pairs of chromosomes attach to the spindle threads at the equator region
Attach at their centromeres

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24
Q

Events during anaphase

A

Centromere of each pair of chromatids splits
Motor proteins, walk along tubulin threads, pull each sister chromatid of a pair to opposite poles
Chromosomes assume a v shape

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25
Q

Events during telophase

A

Separated chromosomes tech poles
Nuclear envelope forms around each set
Cell now contains two nuclei genetically identical to parent cell they arose from

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26
Q

What’s happens in animals and plants during cytokinesis?

A

Animals- plasma membrane folds inwards and nips in the cytoplasm
Plant- an end plate forms where the equator of the spindle was, and new plasma membrane and cellulose cell wall materials are laid down either side along this end plate

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27
Q

What’s a haploid?

A

Having only one set of chromosomes presented by the symbol ‘n’

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28
Q

What are homologous chromosomes?

A

Matching chromosomes, containing the same genes at the same places. They may contain different alleles for some genes

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29
Q

What is meiosis?

A

Type of nuclear division that results in the formation of cells containing half the number of chromosomes of the parent cell

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30
Q

Why does sexual reproduction increase genetic variation?

A

Involved the combining of genetic material from 2 unrelated individuals of the same species, by the process of fertilisation.

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31
Q

Why is genetic variation important?

A

Increases its chances of survival when the environment changes
Some individuals have characteristics that enable them to be better adapted to the change

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32
Q

What are most body cells?

A

Diploid

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33
Q

What must be produced for sexual reproduction to occur?

A

Haploid gametes

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34
Q

What are matching pairs of chromosomes called?

A

Homologous pair

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35
Q

How many divisions are there in meiosis?

A

2

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36
Q

Prophase 1

A

Crossing over.
Chromosomes compromise 2 chromatids
Centrioles at opposite ends of cell
Nuclear envelope disintegrates

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37
Q

Events during prophase 1

A

Chromatin condenses and each chromosome supercoils
Envelope breaks down
Spindle threads of tubulin protein form from centrioles
Chromosomes come together in homologous pairs
Each member of pair consists of 2 chromatids
Crossing over occurs between non sister chromatids. May swap sections so alleles are shuffled

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38
Q

Metaphase 1

A

Spindles attach to centromere at equator

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39
Q

Events during metaphase 1

A

Crossed over chromosomes attach to spindles at centromere
Homologous pairs arranged randomly with members of each pair facing opposite poles of the cell - independent assortment
The way they line up determines how they will segregate independently when pulled apart

40
Q

Anaphase 1

A

Homologous chromosomes r pulled to opposite poles

41
Q

Events during anaphase 1

A

Each pair of homologous chromosomes are pulled apart by motor proteins that drag them along threads of the spindle
Centromere do not divide, each chroma some consists of 2 chromatids
Swapped areas of chromosomes and allele shuffling

42
Q

Telophase 1

A

Nuclear envelope forms

43
Q

Events during telophase 1

A

Two nuclear envelopes form around each set of chromosomes and cytokinesis occurs. Then short interphase where chromosomes uncoil
Each nucleus contains half original number of chromosomes but each chromosome consists of 2 chromatids

44
Q

Prophase 2

A

Centrioles replicate and move to poles

New spindles form at right angles to previous spindle axis

45
Q

Events during prophase 2

A

Nuclear envelopes break down again
Chromosomes coil and condense
Chromatids of each chromosome are not identical
Spindles form

46
Q

Metaphase 2

A

Chromosomes lye on the equator of cell

47
Q

Events during metaphase 2

A

Chromosomes attach, by the centromere, to the equator of the spindle
Chromatids of each chromosome are randomly arranged
Arrangement determines how they separate during anaphase 2

48
Q

Anaphase 2

A

Chromatids mace to poles

49
Q

Events during anaphase 2

A

Centromere divides
Chromatids of each chromosome are pulled apart by motor proteins that drag them along the tubulin threads of the spindle, towards opposite poles
Chromatids randomly segregated

50
Q

Telophase 2

A

4 haploid cells

51
Q

Events during telophase 2

A

Nuclear envelope forms around haploid nuclei
In animals, the 2 cells now divide to give 4 haploid
In plants, a tetrad of four haploid cells is formed

52
Q

How does meiosis produce genetic variation?

A

Crossing over during prophase 1
Independent assortment of chromosomes in anaphase 1 leads to random distribution of maternal and paternal chromosomes of each pair
Independent assortment of chromatids during anaphase 2 leads to further random distribution
Haploid gametes undergo fusion with gametes derived from another organisms

53
Q

What is differentiation?

A

Process by which stem cells become specialised into different types of cell

54
Q

What are epithelial cells?

A

Cells that constitute lining tissue

55
Q

Why are erythrocytes?

A

Red blood cells

56
Q

What are neutrophils?

A

Type of white blood cell that is phagocyte (can ingest microbes and small particles)

57
Q

What are stem cells?

A

Unspecialised cell able to express all of its genes and divide by mitosis

58
Q

Why do multicellular organisms need specialised cells to carry out particular functions?

A

They have a small surface area to volume ratio which means most of their cells are not in direct contact with the external environment

59
Q

What is a zygote a result of?

A

When the ovum is fertilised by the spermatozoon and the two haploid nuclei fuse to give a cell with a diploid nucleus

60
Q

Why do embryonic cells differentiate when certain genes are switched off and other genes are expressed more?

A

Proportion of the different organelles differs from those of other cells
The shape of the cell changes
Some of the contents of the cell changes

61
Q

Name 2 examples of specialised cells in mammals and their function

A

Erythrocytes - carry oxygen from the lungs to restoring cells
Neutrophils - ingest invading pathogens

62
Q

In what ways are erythrocytes adapted to carry out their function?

A

Very small 7.5 micrometers in diameter
Large surface area/volume ratio
Can diffuse across membranes to easily reach all regions inside the cell
Biconcave
Flexible
Well developed cytoskeleton to change shape to fit through narrow capillaries
No nucleus mitochondria or endoplasmic reticulum very little cytoplasm
More space for haemoglobin molecules

63
Q

Neutrophils

A

Twice the size of rbc
Multilobed nucleus
Attracted to and travel towards infection sites by chemotaxis
Ingest bacteria and some fungi by phagocytosis

64
Q

How are spermatozoa?

A

Many mitochondria to carry out aerobic respiration. ATP provides energy for undulipodia to move
Small long and thin therefore move easily
Enzymes in acrosome outer protective covering of ovum
Head contains haploid male gamete nucleus and little cytoplasm

65
Q

Epithelial cells

  • a type
  • location
  • what many have
A

Squamous
Alveoli and intestines lining
Cilia

66
Q

Guard cell definition

A

In leaf epidermis, cells that surround stomata

67
Q

Palisade cells definition

A

Closely packed photosynthetic cells within leaves

68
Q

Root hair cells definition

A

Epidermal cells of your roots with long hair like projections

69
Q

Why are palisade cells well adapted to photosynthesis

A

Long and cylindrical so pack together tightly and have air spaces for diffusion into cells
Large vacuole so chloroplasts are nearer to the periphery of the cell reducing diffusion distance
Contain many chloroplasts
Cytoskeleton threads and motor proteins to move chloroplasts nearer to surface when light intensity Is high and vice versa

70
Q

What do guard cells do to affect the water potential inside them?

A

They use light energy to create ATP
ATP then actively transports potassium ions from surrounding epidermal cells into guard cells, lowering their water potential allowing water to enter

71
Q

Root hair cells adaptions and functions

A

Hair like projections increasing surface area for absorption of water and mineral ions
Ions actively transported in lower water potential bringing water with them
Special carrier proteins in membrane in order to actively transport ions
Produce ATP needed for active transport

72
Q

Tissue definition

A

Group of cells that work together to preform a specific function/set of functions

73
Q

What are the four main tissue types?

A

Epithelial
Connective tissue
Muscle tissue
Nervous tissue

74
Q

Characteristics of epithelial tissue

A

Made up almost entirely of cells
Very close cells to form continuous sheets
Adjacent cells are bound together by lateral contacts eg tight junctions and desmosomes
No blood vessels within them, cells receive nutrients by diffusion from tissue fluid in the underlying connective tissue
Short cell cycles and divide up to 2 or 3 times a day to replace worn or damaged tissue
Specialised to carry out its function eg protection, absorption, filtration, excretion, secretion

75
Q

What does connective tissue consist of?

A

Non living extra cellular matrix containing proteins eg collagen and elastin and polysaccharides eg hyaluronic acid, which traps water
Matrix separates the living cells within the tissue and enables it to withstand forces such as weight

76
Q

Examples of connective tissues

A 
Blood 
Bone 
Cartilage
Tendons
Ligaments 
Skin contains it
77
Q

What are immature cells in cartilage called?

What can they do?

A

Chondroblasts

Divide by mitosis and secrete the extracellular matrix

78
Q

What are the 3 types of cartilage

A

Hyaline cartilage
Fibrous cartilage
Elastin

79
Q

What does hyaline cartilage do?

A

Form embryonic skeleton, covers the ends of long bones in adults, joins ribs to the sternum and is found in the nose

80
Q

What does fibrous cartilage do?

A

In discs between vertebrae in the backbone and in the knee joint

81
Q

What does elastin cartilage do?

A

Makes up outer ear and the epiglottis

82
Q

Describe muscle tissue

A

Well vascularised
Muscle cells are called fibres
Long elongated and contain special organelles called myofilaments made of the protein actin and myosin. These allow tissues to contract

83
Q

What are the 3 types of muscles?

A

Skeletal muscles - cause bones to move
Cardiac muscles - heart beats
Smooth muscle - propels substances along tracts eg in intestine walls, blood vessels, uterus and urinary tracts

84
Q

Driven meristem

A

Area of unspecialised cells within a plant that can divide and differentiate into other cell types

85
Q

Define organ

A

Collection of tissues working together to preform a function/ related functions

86
Q

Define phloem

A

Tissue that carries products of photosynthesis, in solution, within plants

87
Q

Define xylem

A

Tissue that carries water and mineral ions from the roots to all parts of the plant

88
Q

Describe epidermal tissue

A

Consists of flattens cells that, apart from guard cells, lack chloroplasts and form a protective covering over leaves, stems and roots
Some epidermal cells also have walls impregnated with a waxy substance forming a cuticle

89
Q

What are the two types of vascular tissue?

A

Xylem vessel

Phloem sieve tubes

90
Q

Where is meristem tissue found?

A

Tips of roots and shoots

Cambium of vascular bundles

91
Q

Cells in meristem are:

A

Have thin walls containing very little cellulose
Don’t hav chloroplasts
Don’t have a large vacuole
Can divide by mitosis and differentiate into other types of cells

92
Q

How do some cambium cells differentiate into xylem vessels?

A

Lignin is deposited in their cell walls to reinforce and waterproof them however this also kills the cell
Ends of cells break so xylem forms continuous columns with wide lumens to carry water and displaced nutrients

93
Q

How do cambium cells differentiate into phloem?

A

Sieve tubes Lose most their organelles and sieve plates develop between them
Companion cells retain their organelles and continue metabolic functions to provide ATP for active loading of sugars into sieve tubes

94
Q

Main function of organ

-leaf

A

Photosynthesis

95
Q

Organ root

A

Anchorage
Absorption of mineral ions and water
Storage

96
Q

Organ stem

A 
Support
Holds leaves up to expose to more sun light
Transportation of water and minerals
Transport of products of photosynthesis 
Storage of products of photosynthesis
97
Q

Flower organ

A

Sexual reproduction

Biology (6 decks)

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