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Biology > Topic 2 - Cells and Life > Flashcards

Topic 2 - Cells and Life Flashcards

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1
Q

mitosis defnition

A

when a cell reproduces itself to form two genetically identical diploid daughter cells

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2
Q

6 stages of cell cycle and mitosis

A

I PMAT C

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3
Q

What happens in interphase?

A
  • cell needs to grow and increase amount of sub - cellular structures such as mitochondria and ribosomes
  • it duplicates its DNA and forms X - shaped chromosomes
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4
Q

What happens in prophase?

A
  • chromosomes condense getting shorter and fatter
  • nuclear membrane breaks down
  • centrioles are copied and move to opposite ends of cell
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5
Q

What happens in metaphase?

A
  • chromosomes line up at middle of the cell ( equator )
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6
Q

What happens in anaphase?

A
  • spindle fibres extending from the centriole contract separates 2 sister chromatids at the centromere
  • sister chromatids go towards opposite ends of cell
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7
Q

What happens in telophase?

A
  • new nuclear membranes form around each of the sets of chromosomes
  • 2 daughter nuclei in parent cytoplasm
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8
Q

What happens in cytokinesis?

A

cytoplasm separates to form two genetically identical daughter cells each with 2 sets of chromosomes

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9
Q

What are the three uses of mitosis

A
  • growth
  • repair tissue by replacing damaged cells
  • reproduce by asexual reproduction to produce genetically identical clones
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10
Q

problem with asexual reproduction

A
  • there is no genetic variation in the species so are all susceptible to same diseases
  • no evolutionary potential
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11
Q

how do cells know when to stop dividing?

A
  • once we have reached adult size or repaired damaged cells a gene in our nucleus tells the cell to stop dividing
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12
Q

how do cancers form?

A
  • a mutation may occur in that gene resulting in a cell that divides by mitosis uncontrollably
  • makes masses of undifferentiated cells known as tumours
  • these tumours can spread and invading normal tissue, causing cancer
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13
Q

cell differentiation

A

when stem cells express the correct genes to make the proteins they need, allowing them to differentiate

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14
Q

why are specialised cells important for the human body?

A

it helps multicellular organisms to work more efficiently because different cell types can carry out different functions

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15
Q

cell elongation

A

where a plant cell expands making the plant grow

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16
Q

growth in animals

A
  • all growth in animals is due to cell division
  • when they’re young cell division happens at a fast rate
  • once animals reach adult size, cell division is mostly only for repair
  • cell differentiation lost at an early stage
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17
Q

growth in plants

A
  • growth in height mainly due to cell elongation
  • cell division just happens in the meristems ( tips of r&s)
  • plants grow continuously so continue to differentiate to develop new parts
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18
Q

percentile charts

A

used to assess a child’s growth over time and compare it to children the same age and gender

19
Q

what are stem cells?

A

stem cells are undifferentiated cells that are not yet specialised for a specific function

20
Q

totipotent embryonic stem cells

A

can differentiate into every type of specialised cell, so very important for growth + development of human body

21
Q

multi-potent adult stem cells

A

they are only found in certain places (e.g : bone marrow ) and can only differentiate into certain specialised cells

22
Q

what are adult stem cells used for in the body?

A

they are used to replace damaged cells

23
Q

adult cells used in medicine

A
  • people with blood diseases can have bone marrow transplants which contain adult stem cells
  • these adult stem cells can differentiate to turn into new blood cells replacing faulty ones
24
Q

how could embryonic stem cells be used in medicine

A
  • under certain conditions, could be stimulated to differentiate into any kind of specialised cell
  • can be used to replace faulty cells in tissues with no stem cells like spinal cord
25
Q

issues involving using stem cells

A
  • tumour development : stem cells divide very quickly
  • disease transmission : donor stem cell could be infected with virus
  • rejection : immune system may recognise cells as foreign and trigger a response to get rid of them.
26
Q

ethical issue involving embryonic stem cell

A
  • human embryos shouldn’t be used as each one is a potential human life
27
Q

what are sensory receptors?

A
  • groups of cells that detect stimuli
    (changes in the environment) and initiate responses to them
28
Q

CNS ( Central Nervous System )

A

Consists of the brain and spinal cord and co-ordinates and controls the human body

29
Q

what are effectors?

A
  • muscles or glands that respond to nervous impulses and bring about a response to a stimulus
30
Q

transmission of information to and from CNS

A

stimulus -> receptor -> sensory neurone -> relay neurone(CNS) -> motor neurone -> effector -> response

31
Q

sensory neurones

A

they carry information as electrical impulses from the sensory receptor to the CNS

32
Q

relay neurones

A

they carry information as electrical impulses from the sensory neurones to the motor neurones and found in CNS

33
Q

motor neurones

A

they carry information as electrical impulses from the CNS to the effector

34
Q

dendrons

A

carry electrical impulses towards cell body

35
Q

axons

A

carry electrical impulses away from cell body

36
Q

myelin sheath

A

acts as an electrical insulator around axon, speeding up rate of electrical impulse

37
Q

what are synapses?

A

a minute gap or junction between neurones through which they communicate with each other

38
Q

how do electrical impulses get transmitted between neurones?

A
  • when an electrical impulse reaches the end of the first neurone
  • it triggers the release of neurotransmitters ( chemical messengers )
  • they diffuse down the concentration gradient and bind to receptor on next neurone
  • new electrical impulse generated and moves down next neruone
39
Q

why are synapses useful?

A
  • only one end of neurone can make neurotransmitters so it makes sure impulses only travel in 1 direction
  • slow down the passage of information so it isn’t harmful
40
Q

what are reflexes?

A
  • they are exceedingly rapid, automatic responses to certain stimuli.
  • they protect our bodies from harm by minimising exposure to harmful stimuli
41
Q

how do reflexes do this?

A
  • it minimises the distance impulses have to travel around the body, so minimises number of neurones and synapses that must be crossed
  • it goes through the unconscious part of brain
42
Q

example of how reflex arc works?

A

check 23/3/23 in Bio exercise book

43
Q
A

Biology (9 decks)

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