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BIOLOGY > SB2 - CELLS & CONTROL > Flashcards

SB2 - CELLS & CONTROL Flashcards

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1
Q

mitosis definition

A

nuclear division that produces two genetically identical diploid daughter cells

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2
Q

in humans, diploid cells contain __ PAIRS of chromosomes

A

23

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3
Q

mitosis is required for: (3)

A
  • growth; produces new cells
  • repair; to replace damaged or dead cells
  • asexual reproduction; mitosis produces offspring that are genetically identical to the parent
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4
Q

stages of mitosis (5)

A

IPMAT
INTERPHASE: just before mitosis, the DNA in the nucleus copies itself exactly (forming X-shaped chromosomes)
PROPHASE: DNA condenses, chromosomes become visible
METAPHASE: chromosomes line up on the equator of the cell
ANAPHASE: fibres split the chromosomes down the centre and pull one chromatid to either
side of the cell
TELOPHASE: new membranes form around the chromosomes at either end of the cell
-> then cytokinesis

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5
Q

describe what happens in the interphase

A

INTERPHASE: just before mitosis, the DNA in the nucleus copies itself exactly (forming X-shaped chromosomes)

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6
Q

describe what happens in the prophase

A

PROPHASE: DNA condenses, chromosomes become visible

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7
Q

describe what happens in the metaphase

A

METAPHASE: chromosomes line up on the equator of the cell

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8
Q

describe what happens in the anaphase

A

ANAPHASE: fibres split the chromosomes down the centre and pull one chromatid to either side of the cell

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9
Q

describe what happens in the telophase

A

TELOPHASE: new membranes form around the chromosomes at either end of the cell

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10
Q

describe what happens in cytokinesis

A
  • the cell splits
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11
Q

cancer is caused as a result of _______

A
  • mutations in the DNA of cells that lead to uncontrolled cell growth and division
  • this can result in the formation of a tumours (a mass of cells)
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12
Q

name the two main types of tumour

A
  • benign tumours
  • malignant tumours
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13
Q

benign tumours are _______

A

growths of abnormal cells which are CONTAINED in one area
- crucially, benign tumours do not invade other parts of the boyd
- this means these tumours are not considered cancerous

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14
Q

malignant tumours are _______

A
  • cancerous cells.
  • the cells of these tumours invade neighbouring tissues and spread to different parts of the body via the blood and lymphatic system where they form secondary tumours
  • malignant tumours are more likely to disrupt the functioning of the organ (as they invade healthy tissue) and the organs they spread to
  • this is why they are dangerous and how they lead to death
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15
Q

growth definition

A

a permanent increase in size or mass

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16
Q

key processes of growth in plants and animals (2)

A

cell division - mitosis
cell differentiation - development of specialised features creating specialised cells

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17
Q

describe cell elongation

A
  • only happens in plants.
  • where hormones (such as auxin) cause cells to grow longer in response to certain stimuli eg. sunlight
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18
Q

indicator measurements for growth of babies (3)

A
  • mass
  • length
  • head circumference
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19
Q

issues that can be identified by comparing with growth charts (4)

A
  • malnutrition
  • obesity
  • inconsistencies across different measurements eg. a large baby with a small head
  • sudden changes in trend (which may indicate expression of a new health problem)
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20
Q

if a baby is on the 25th percentile for mass, it means that they are heavier than __% of children their age and heavier than __% of children their age

A

25th percentile =
heavier than 25§
lighter than 75%

21
Q

differentiation is …

A

when a cell undergoes structural adaptations which enable them to perform specific functions within the organism

22
Q

in an animal, most cells differentiate at an _____ stage of its development

A

early

23
Q

animals cells ____ the ability to differentiate after they have become specialised early in the life of the animal

A

lose

24
Q

plant cells ______ the ability to differentiate throughout the life of a plant

A

retain

25
Q

a stem cell is …

A
  • an undifferentiated cell of an organism that is capable of dividing to produce many more cells of the same type
  • in addition, stem cells can give rise to other cell types through the process of differentiation
26
Q

embryonic stem cells are able to form ___ different cell types

A

all

27
Q

adult stem cells are able to form ______ different cell types

A

a limited number

28
Q

adult stem cells are predominantly used to …

A

replace cells lost through damage or produce new cells for growth

29
Q

in animals, adult stem cells can be found in the … (4)

A
  • bone marrow
  • skin
  • organs such as the liver and brain
  • umbilical cord
30
Q

in plants, stem cells are found in the …

A

root and shoot tips, in the MERISTEM TISSUE

31
Q

meristem cells are …

A

unspecialised cells that can differentiate into the cells needed by the plant in regions where growth is occurring

32
Q

it is possible to use plant stem cells to …

A

clone plants with desired characteristics eg. resistance to certain diseases

33
Q

how can adult stem cells be used in medicine?

A
  • adult stem cells can be cultured in a lab and made to differentiate into specialised cells but into fewer cell types than is possible with embryonic stem cells
  • stem cells are already used to treat some diseases eg. leukaemia but there is huge potential for stem cells to be used to cure many more diseases in the future eg. diabetes and paralysis
34
Q

how can embryonic stem cells be used in medicine?

A
  • modern scientific techniques mean that it is possible to grow human embryos in a lab to extract embryonic cells from them
  • these embryonic cells can then be stimulated to differentiate into most types of specialised cell
  • as a result, they are potentially very effective in treatment of certain diseases or to repair damaged organs by growing new tissue from stem cells
35
Q

benefits of using stem cells in medicine (3)

A
  • great potential to treat a wide variety of diseases
  • organs developed from a patients own stem cells are less likely to be rejected and they don’t need to wait for an organ donation
  • adult stem cells are already used successfully in a variety of treatments acting as proof of the benefits
36
Q

risks / issues of using stem cells in medicine (3)

A
  • stem cells cultured in a lab could become infected with a virus which could be transmitted to the patient
  • risk of cultured stem cells accumulating mutations that can lead to the developing into cancer cells
  • low number of stem cell donors
37
Q

social / ethical issues of using stem cells in medicine

A
  • expensive so not an option for everyone
  • educating the public sufficiently about what stem cells can and cannot be used for
  • should an embryo be treated as a person with human rights or as a commodity?
38
Q

the central nervous system (CNS) includes the _____ alongside the ______ ____

A

brain, spinal cord

39
Q

the spinal cord is formed from …

A

a bundle of neurones which branch off to different parts of the body

40
Q

the brain is made of …

A

billions of interconnected neurones and is responsible for controlling complex behaviours

41
Q

regions of the brain (3)

A
  • cerebral cortex or cerebrum
  • cerebellum
  • medulla oblongata
42
Q

cerebral cortex / cerebrum: location and role

A
  • outer layer of the brain which is divided into two hemispheres (left and right)
  • responsible for processes such as intelligence, memory, consciousness and personality
43
Q

cerebellum: location and role

A
  • underneath the cerebral cortex
  • responsible for balance, muscle coordination and movement
44
Q

medulla oblongata: location and role

A
  • under cerebellum
  • controls unconscious activities such as heart rate and breathing
45
Q

CT scans - summary

A
  • uses X-rays which are fired at the brain from multiple different directions
  • shows physical structures of the brain and allows visualisation of any tissue damage
  • don’t directly show functions of each region but symptoms caused by tissue damage can allow neurologists to work out which regions of the brain are responsible for which functions
  • risks: exposure to X-ray radiation, which is given at a higher level than in a normal X-ray
46
Q

PET scans - summary

A
  • use radioactive tracers which collect in areas where there is an increased blood flow eg. active regions in the brain as well as cancerous tissues (which have a higher blood flow than healthy tissues)
  • neurologists can use the images to study the structure and function of the brain in real time
47
Q

why is it difficult to treat damage or disease to the CNS? (4)

A
  • cancerous tumours can be located deep into the brain or spinal cord so cannot be surgically removed at all from some regions
  • tissues of the nervous system don’t repair in the same way other tissues do
  • we do not know exactly which regions of the brain are responsible for which functions
  • any potential treatment risks further damage occurring -> accidental damage could lead to speech or motor issues, or changes to personality which are permanent
48
Q

the human nervous system contains of the ___ and the ___

A
  • central nervous system (CNS); the brain and spinal chord
  • peripheral nervous system (PNS); all of the nerves in the body

BIOLOGY (6 decks)

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