cells and control Flashcards
(103 cards)
1
Q
chromosomes
A
coils of DNA
2
Q
diploid
A
23 pairs of chromosomes / 46 total
3
Q
haploid
A
23 chromosomes
4
Q
Which body cells are haploid?
A
sex cells / gametes
5
Q
Why are gametes haploid?
A
so that they can combine during fertilisation to form the diploid amount
6
Q
cell cycle
A
a series of steps that a cell must undergo in order to divide
7
Q
When does the cell cycle start?
A
when a cell has been produced by cell division
8
Q
When does the cell cycle end?
A
with the cell dividing to produce two identical cells
9
Q
What are the two stages of the cell cycle?
A
interphase and mitosis (and cytokinesis)
10
Q
What two things happen during interphase and why is each thing happening?
A
- The chromosomes are being copied into two sister chromatids attached to each other at the centromere. This is so that each daughter cell is genetically identical to this parent cell. 2. The cell grows in size and creates more organelles so that once the daughter cells divide, they have enough organelles to survive.
11
Q
Is the DNA visible as chromosomes with a light microscope during interphase?
A
No
12
Q
mitosis
A
the stage in the cell cycle when the cell reproduces itself by splitting in two to form two genetically identical offspring
13
Q
When does cytokinesis occur?
A
shortly before the end of telophase
14
Q
What happens during cytokinesis?
A
The cytoplasm and cell membrane divide to produce two genetically identical diploid daughter cells, each with its own nucleus.
15
Q
four stages of mitosis
A
prophase, metaphase, anaphase, telophase
16
Q
What three things occur during prophase?
A
- The sister chromatids condense, becoming shorter and fatter. 2. The nuclear envelope breaks down to allow the sister chromatids to move around in the cell cytoplasm. 3. The centrioles begin to move to opposite poles of the cell.
17
Q
What two things happen during metaphase?
A
- The sister chromatids line up at the cell’s equator. 2. The sister chromatids are moved by spindle fibres, which extend out from the centrioles and connect to the sister chromatids’ centromeres.
18
Q
What two things happen during anaphase?
A
- The spindle fibres shorten, separating the sister chromatids at the centromere into daughter chromosomes. 2. These daughter chromosomes are pulled by the spindle fibres to opposite poles of the cell.
19
Q
What happens during telophase?
A
New nuclear envelopes form around each group of daughter chromosomes, to form two daughter nuclei in the parent cell cytoplasm.
20
Q
Which three things is mitosis important for?
A
growth, repair, and asexual reproduction
21
Q
Why is mitosis important in growth?
A
so that an organism can grow to adult size by making more cells
22
Q
Why is mitosis important in repair?
A
so that an organism can replace damaged cells by creating new cells
23
Q
Why is mitosis important in asexual reproduction?
A
so that an organism can reproduce by generating genetically identical cells, or clones
24
Q
Describe the division of a cell by mitosis.
A
the production of two daughter cells, each with identical sets of chromosomes in the nucleus to the parent cell, and that this results in the formation of two genetically identical diploid body cells
25
What is cancer caused by?
mutations in a cell's DNA
26
What are tumours and how are they formed?
Some cells which lose control of their cell cycle keep dividing to produce masses of undifferentiated cells called tumours.
27
How do tumours cause cancer?
They spread and destroy organs
28
three treatments for cancer
surgery, chemotherapy, and radiotherapy
29
How can surgery be used to treat cancer?
by cutting out and removing the tumour if accessible
30
How can chemotherapy be used to treat cancer?
use drugs that are toxic to cells that keep dividing to kill tumours
31
How can radiotherapy be used to treat cancer?
use targeted beams of radiation to kill tumours
32
What are percentile charts used for and why?
To monitor the rate at which an organism of interest is growing, so that an overall pattern in development can be seen and any problems identified.
33
three measures to monitor the growth of babies
head circumference, mass, and length
34
A baby born at the 25th percentile for mass is [...] or the [...] as [...]% of babies of the [...].
A baby born at the 25th percentile for mass is heavier or the same weight as 25% of babies of the same sex.
35
two ways abnormal growth may be identified using percentile charts
1. an increase or decrease of two or more percentile lines over time 2. an inconsistent pattern (a small baby with a large head
36
two examples of problems which can be identified from abnormal head circumference growth
microcephaly (too small) hydrocephalus (too large)
37
three examples of problems which can be identified from abnormal mass growth
childhood obesity (too fast) malnutrition (too slow) potential troubles with feeding or digestion (too slow)
38
two examples of problems which can be identified from abnormal length growth
1. growth hormone issues 2. potential underlying health issues
39
two things growth in an organism may result in
an increase in size, or mass (or both)
40
two processes by which animal growth occurs
cell division, and cell differentiation
41
Cell division happens by [...].
Cell division happens by mitosis.
42
cell differentiation
the process by which a cell changes to become specialised for its function
43
How do cells differentiate?
by expressing the correct genes to allow them to make the proteins they need to give their specialised shape and function
44
Why are specialised cells important for multicellular organisms?
allows them to work more efficiently because different cell types can carry out different functions
45
three processes by which growth in plants occurs
cell divison, cell elongation, and cell differentiation
46
Where does cell division in plants happen?
meristems
47
meristems
undifferentiated stem cells in plants usually found grouped together
48
"two types of meristem and where they're found"
apical meristems are found in the tips of roots and shootslateral meristems are found on the sides of the plant's stem in a bud
49
cell elongation and how it causes growth
where a plant cell expands by taking in water and carbon dioxide, making the cell bigger, which makes the plants grow
50
totipotent stem cells
stem cells which are able to differentiate into every type of specialised cell in the human body
51
Where are totipotent stem cells found?
early embryos 1-16 cell size
52
pluripotent stem cells
stem cells which are able to differentiate into most, but not every type of specialised cell in the human body
53
Where are pluripotent stem cells found?
early stem cells beyond 16 cell size
54
multipotent stem cells
stem cells which are able to differentiate into a small number of specialised cell types
55
Adult stem cells are [...] stem cells.
Adult stem cells are multipotent stem cells.
56
Where are multipotent stem cells found?
"in some of the body's tissues"
57
three areas in the human body where adult stems cells are found
skin, liver, and bone marrow
58
What can meristems be used to do?
produce clones of an ideal parent plant
59
Why may one want to clone a parent plant?
1. desirable features, such as disease resistance 2. for research 3. prevent a plant from becoming extinct
60
two diseases adult stem cells are used to cure
1. leukaemia (cancer affecting white blood cells) 2. sickle cell anaemia (disease affecting blood cells)
61
How can adult stem cells be used to cure diseases?
by an allogeneic transplant
62
How is an allogeneic transplant carried out?
Healthy blood stem cells are taken from the bone marrow of a donor and inserted into the patient's bone marrow, so they produce healthy blood cells.
63
three diseases embryonic stem cells could potentially be used to cure and how
"1. diabetes: by replacing faulty cells with insulin producing cells 2. Alzeimer's: produce new neural cells 3. paralysis from spinal cord injuries: produce new nerve cells"
64
three potential benefits associated with the use of (embryonic) stem cells in medicine
They can be used to replace diseased or damaged body parts. Unwanted embryos from IVF clinics could be used as they would be otherwise destroyed. They allow for research into the process of differentiation.
65
three potential risks associated with the use of (embryonic) stem cells in medicine
tumour development, disease transmission, and rejection
66
How can the use of (embryonic) stem cells in medicine lead to tumour development?
Since stem cells divide very quickly, if scientists are unable to control the rate at which the transplanted cells divide in a patient, a tumour may develop.
67
How can the use of (embryonic) stem cells in medicine lead to disease transmission?
If donor stem cells are infected with a virus, an infection can be transferred to the patient.
68
How can the use of (embryonic) stem cells in medicine lead to rejection?
If the transplanted cells are not grown with the patient's own stem cells, the patient's immune system may reject the cells and destroy them.
69
How can rejection of transplanted stem cells be prevented?
The patient can take immunosuppressant drugs
70
negative effect of taking immunosuppressant drugs
more susceptible to diseases and infections
71
The use of embryonic stem cells raises [...] issues.
The use of embryonic stem cells raises ethical issues.
72
ethical issue raised by the use of embryonic stem cells
some believe human embryos shouldn't be used for experiments since each one is a potential human life
73
[...] and [...] issues can be prevented by the use of iPSC (induced pluripotent stem cells)
Rejection and ethical issues can be prevented by the use of iPSC (induced pluripotent stem cells)
74
Rejection and ethical issues can be prevented by the use of [...] ([...])
Rejection and ethical issues can be prevented by the use of iPSC (induced pluripotent stem cells)
75
How are iPSC (induced pluripotent stem cells) made?
healthy multipotent adult stem cells are given growth factors in the lab to turn them back into pluripotent stem cells
76
stimuli
changes in our environment
77
three examples of stimuli
temperature, sound, and light
78
sensory receptors
groups of cells that detect stimuli and initiate responses to them
79
function of the human nervous system
allows us to detect stimuli and coordinate responses to stimuli
80
two parts of the human nervous system
Central Nervous System (CNS), Peripheral Nervous System (PNS)
81
parts of the CNS
brain, spinal cord
82
role of the CNS
coordination and control
83
parts of the PNS
all parts of the human nervous system, except the brain and spinal cord
84
role of the PNS
transmit information as electrical signals (nerve impulses) between the CNS and the rest of the body
85
two types of nerve cell (neurone) in the PNS
sensory neurone, motor neurone
86
nerve
bundle of neurones
87
two adaptations of neurones
long axons and dendrons, myelin sheath
88
How do long axons and dendrons make neurones more effective?
These speed up the impulse since synapses slow the electrical signals (nerve impulses) down, so one long neurone is more efficient.
89
How does the myelin sheath make neurones more effective?
Insulates the axon / dendron, speeding up the electrical signal (nerve impulse).
90
function of sensory neurones
transmit information about stimuli as electrical signals (nerve impulses) from receptors to the CNS
91
function of motor neurones
transmit "instructions" from the CNS as electrical signals (nerve impulses) to effectors to initiate an appropriate response
92
two examples of effectors and appropriate responses
muscles, which contract glands, which secrete hormones, such as adrenaline
93
function of relay neurones
transmit information as electrical signals (nerve impulses) from sensory neurones to motor neurones, and are found in the CNS
94
synapse
minute gap / cleft about 20 nm wide which serves as the connection between two neurones
95
neurotransmitters
chemicals which diffuse across the synaptic cleft to transmit the electrical signal (nerve impulse) to the next neurone
96
function of a synapse
slow down the transmission of electrical signals (nerve impulses)
97
Explain what occurs when an electrical signal (nerve impulse) reaches a synapse.
When an electrical signal (nerve impulse) reaches the end of one neurone, neurotransmitters are released, which diffuse across the synaptic cleft, and bind to receptors in the membrane of the next neurone, which starts off a new electrical signal (nerve impulse) in the next neurone.
98
reflexes
fast, automatic responses to certain stimuli, from receptor to effector
99
Why do reflexes have to be fast?
to reduce the chance of or to prevent injury
100
What does it mean for reflexes to be automatic?
there is no conscious thought
101
reflex arc
passage of information in a reflex
102
Where are the neurones in reflex arcs located?
in the spinal cord or an unconcscious part of the brain
103
Describe what occurs during a reflex arc.
When a stimulus is detected by receptors, electrical signals (nerve impulses) transmit along a sensory neurone in the PNS. The electrical signals (nerve impulses) transmit along a relay neurone in the CNS via a synapse. The electrical signals (nerve impulses) transmit along a motor neurone via a synapse. The electrical signals (nerve impulses) reach the effector, which initiates a response.
