Cells And Control Flashcards
(155 cards)
1
Q
Most of the time where does DNA exist!?
A
In the nucleus as thin strands
2
Q
When the cells containing nuclei are ready to divide what happens to the DNA!?
A
It copies itself then could and condenses to form chromosomes
3
Q
What is DNA!?
A
Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being.
4
Q
What are chromosomes!?
A
The structure made of DNA that codes for all the characteristics of an organism.
5
Q
How many chromosomes does each human body cell contain!?
A
46 chromosomes
6
Q
How many chromosomes are in a pair!?
A
23
7
Q
Each chromosome in a pair carries the same types of what!?
A
Genes
8
Q
What is the 23rd pair!?
A
The sex chromosomes
9
Q
Describe the pair of chromosomes in females….
A
the two chromosomes are identical in shape. These are X chromosomes. Females are referred to as XX
10
Q
Describe the pair of chromosomes in a male…..
A
In males, one of the chromosomes is different in shape. This is a Y chromosome. Males are referred to as XY.
11
Q
When do cells divide!?
A
Cells divide when:
an organism grows
an organism becomes damaged and needs to produce new cells for repair
organisms like bacteria reproduce asexually
12
Q
What is essential that new cells contain!?
A
It is essential that any new cells produced contain genetic information that is identical to the parent cell.
13
Q
What is the cell cycle!?
A
The events that lead to cell division and DNA replication.
14
Q
What is the equation for length of time in a phase!?
A
Observed number of cells at that stage/total number of cells observed x total length of time of cell cycle
15
Q
What is the definition of mitosis!?
A
A type of cell division which produces daughter cells identical to the parent.
16
Q
Describe the process of mitosis!?
A
Mitosis is a type of cell division in which a diploid body cell copies itself and finally divides into two identical diploid daughter cells. The daughter cells are clones of each other. Every base pair of their DNA is identical.
17
Q
What happens in the first phase of the cell cycle and what is it called!?
A
Interphase
The cell spends most of its life in this phase. The DNA in chromosomes copies itself ready for mitosis.
18
Q
What happens in the second stage of the cell cycle !? And what is it called!?
A
Prophase
The DNA in chromosomes and their copies condenses to become more visible. The membrane around the nucleus disappears.
19
Q
What happened in the third stage of the cell cycle !? And what is it called!?
A
MetaphaseChromosomes and their copies line up in the middle of the cell.
20
Q
What happens in the fourth stage of the cell cycle and what is it called!?
A
Anaphase
Chromosomes and their copies are pulled to different ends of the cell
21
Q
What is the fifth stage of the cell cycle!?
A
Telophase
New membranes form around the chromosomes at each end of the cell.
22
Q
What happens it final stage of the cell cycle!?
A
CytokinesisThe cell membrane pinches in and eventually divides into two daughter cells.
23
Q
What 4 stages of the cell cycle are part of mitosis!?
A
prophase, metaphase, anaphase and telophase.
24
Q
When do cells use mitosis!?
A
Cells grow then divide by mitosis only when we need new ones. This is when we’re growing or need to replace old or damaged cells.
25
What happens when a cell becomes cancerous!?
When a cell becomes cancerous, it begins to grow and divide uncontrollably. New cells are produced even if the body does not need them. A group of cancerous cells produces a growth called a tumour.
26
What are the 2 types of tumour!?
Benign and malignant
27
What is the definition of benign!?
A tumour that is not cancerous and cannot spread to other areas of the body.
28
What are the characteristics of a benign tumour!?
Grow slowly.
Usually grow within a membrane, so can easily be removed.
Do not invade other parts of the body.
29
What is the definition of a malignant tumour!?
A fast-growing tumour that is cancerous and can invade and spread to other areas of the body.
30
What are the characteristics of a malignant tumour!?
Grow quickly.
Invade neighbouring tissues and can spread to other parts of the body in the bloodstream.
As the tumour grows, cancer cells detach and can form secondary tumours in other parts of the body.
This process is called metastasis.
31
Are cancer cells specialised or undifferentiated!?
Cancer cells are undifferentiated – they do not carry out their normal function.
32
At some point what may occur due to cancer!?
At some point, secondary tumours may develop
33
What causes cancer!?
Genetic factors
Chemicals and other agents called carcinogens
34
What is a carcinogen!?
chemical or other agent that causes cancer.
35
What do carcinogens cause!?
Carcinogens cause cancer by damaging DNA. Carcinogens cause mutations to occur. A single mutation will not cause cancer. Several are required for this to occur. For this reason, we are more likely to develop cancer as we get older.
36
List the lifestyle factors that are likely to cause cancer…..
viruses
the chemical carcinogens
alcohol intake
exposure to ultraviolet radiation
diet
37
Give an example of viruses that can unfortunately lead to cancer….
viruses linked with cancer, such as the human papilloma virus (HPV), being spread from person to person through sexual intercourse
38
Give an example of a chemical carcinogen that can unfortunately lead to cancer!?
the chemical carcinogens in cigarette smoke increasing the risk of lung cancer
39
Give an example of how alcohol can unfortunately lead to cancer!?
alcohol intake is linked with certain cancers
40
Give an example of how exposure to ultraviolet light can unfortunately cause cancer!?
exposure to ultraviolet radiation, part of which is ionising, during sunbathing or outdoor activities, leading to the development of skin cancers
41
Give an example of how diet can unfortunately lead to cancer……
diet, including fat and salt intake, increases the risk of cancer
42
List the industrial and environmental factors at work that can unfortunately lead to cancer…..
exposure to ionising radiation increases the risk factor
exposure to chemical carcinogens
43
What is another type of risk that can unfortunately potentially lead to cancer!?
There are also genetic risk factors for some cancers.
44
How are plants and animals produced!?
Animals and plants produced by sexual reproduction begin life as a single cell, a fertilised egg or zygote.
45
How must plants and animals use mitosis!?
These cells must divide by mitosis to produce a multicellular organism.
46
What is a zygote!?
A fertilised egg cell.
47
Where does mitosis occur in animal cells!?
Mitosis happens throughout the bodies of animals
48
Where does mitosis occur in plants!?
only occurs in specific regions of plants. These are called meristems and are found in the tips of roots and shoots. Here new cells are formed.
49
What is a meristem!?
A region in plant shoots and roots in which cells are dividing, and so are undergoing mitosis.
50
What is cell elongation!?
Plant cells are also able to become longer as they grow. This process is called cell elongation
51
Where does cell elongation occur in a plant!?
occurs throughout the plant, not just in the meristems.
52
Does cell elongation occur in animals!?
No
53
What must multicellular animals and plants also do!?
Differentiate
54
Why must multicellular plant and animal cells differentiate!?
so that its cells develop features that enable them to fulfil specific roles. Cells that have differentiated have become specialised
55
What does differentiate mean!?
When an unspecialised cell becomes a more specialised cell type.
56
What would happen if plant and animal cells didn’t become specialised!?
Without this specialisation, complex multicellular animals and plants would not exist.
57
What are cells in the circulatory system specialised to do!?
Transport substances. Defend the body. Regulate temperature.
58
What are cells in the excretory system specialised to do!?
Remove waste products and unwanted substances. Regulate the water content of the body.
59
What are cells of the muscular system specialised to do!?
Bring about movement
60
What are cells of the nervous system specialised to do!?
Respond to internal and external stimuli and conditions. Carry messages for the body to work as a coordinated whole.
61
What are the cells of the respiratory system specialised to do!?
Deliver oxygen for respiration and remove waste.
62
What are the cells of the reproductive system specialised to do!?
Bring about fertilisation to produce new offspring.
63
What are the cells of the skeletal system specialised to do!?
To bring about movement. Support and protect internal structures. Produce blood cells. Store and release calcium.
64
What are the cells of the palisade mesophyll found in a leaf cell specialised to do!?
Carry out photosynthesis
65
What are the cells of the spongy mesophyll found in a leaf cell specialised to do!?
Allow gases to circulate for the exchange of gases between the leaf and the environment. Carry out photosynthesis.
66
What are the cells of the guard cells found in a leaf specialised to do!?
Open and close to control the exchange of gases – carbon dioxide, water vapour and oxygen.
67
What are the cells of the phloem (sieve tubes) found in a leaf specialised to do!?
Transport products of photosynthesis, including sugars and amino acids, from the leaf to where they are needed.
68
What are the cells of the companion cells found in a leaf specialised to do!?
Provide the energy required for transporting substances in sieve tubes.
69
What are the cells of the xylem (xylem vessels) found in a leaf specialised to do!?
Transport water and dissolved minerals from the roots, up the plant.
70
What are the cells of the growing points in the meristem found in a leaf specialised to do!?
Produce new cells as they divide.
71
List all of the ways that the growth of babies is measured…..
Mass (kg)
Length (cm)
Head circumference (cm)
72
What is the name of the graph that all 3 measurements can be monitored on!?
Percentile growth charts
73
What is a percentile growth chart!?
A chart used to compare the growth of a baby to the growth of other babies.
74
What are stem cells!?
A cell found in foetuses, embryos and some adult tissues that can give rise to a wide range of other cells.
75
Are stem cells specialised cells!?
No because
Stem cells are cells that have not undergone differentiation. A cell which has not yet become specialised is called undifferentiated.
76
What develops from a fertilised egg!?
An embryo develops from a fertilised egg. Cells at early stages in the development of the embryo are stem cells.
77
What happens when an embryonic stem cell is removed from embryo!?
If embryonic stem cells are removed from the embryo they will differentiate into any cell type.
78
What is an adult stem cell!?
A type of stem cell found in specific locations in adults. Adult stem cells can only differentiate into a limited number of related cell types.
79
What is an embryonic stem cell!?
A type of stem cell found in the embryo, capable of dividing into almost any cell type.
80
Where are adult stem cells found!?
Adult stem cells can be found in:
nose
brain
eyes
blood
heart
liver
bone marrow
skin
muscle
81
Where are adult stem cells found in the body!?
They are found in limited numbers and in certain locations in the body
82
Describe how adult stem cells differentiate…..
Adult stem cells can differentiate into related cell types only
83
What can bone marrow cells differentiate into!?
bone marrow cells can differentiate into blood cells and cells of the immune system, but not other cell types.
84
Give a definition of the immune system…..
The body's defence system against entry of any foreign body, including pathogens and agents such as pollen grains. The role of the immune system is to prevent disease.
85
What is bone marrow!?
Soft tissue found inside bones that produces new blood cells.
86
Where does cell division in plants take place!?
In regions called meristems
87
How do the stem cells in meristems differentiate!?
Cells of the meristem can differentiate to produce all types of plant cells at any time during the life of the plant. The main meristems are close to the tip of the shoot, and the tip of the
88
In a growing shoot new cells are being produced constantly near the tip. What happens as the cells become older!?
As the cells become older, further away from the tip, they become differentiated. They enlarge and develop a vacuole.
89
What is a vacuole!?
A space within the cytoplasm of plant cells that contains cell sap.
90
What are the advantages of adult stem cells in plants being able to differentiate into any type of cell!?
We can clone them Too….
1.Grow orchids and house plants quickly and cheaply
2.Conserve endangered species
3.Clones of plants that have been genetically modified
91
How can growing human stem cells in a lab help cure diseases such as diabetes!?
By replacing the insulin produced in cells in the pancreas
Or
Enable people paralysed by spinal injuries to walk again by regrowing the spinal nerves
92
What are the clinical challenges of developing embryonic stem cells in a lab !?
to encourage the stem cells to grow and develop into the types of cells we need instead of something we don’t need
93
What are the ethical challenges of growing embryonic stem cells in a lab!?
Stems cells Come from human embryos
94
How can adult stem cells have a positive impact clinically!?
Bone marrow transplants
95
Way can stem cells do that could help medically!?
Stem cells can divide to produce new cells, which can then divide into different cell types. They therefore have the potential to be transplanted into patients to treat medical conditions and disease
96
What is a stem cell!?
A cell found in foetuses, embryos and some adult tissues that can give rise to a wide range of other cells.
97
When are bone marrow transplants given!?
1.cases of blood cell cancer such as leukaemia and lymphoma
2.when blood cells have been destroyed by cancer treatment
98
What can the cells in bone marrow differentiate into!?
Bone marrow cells will differentiate into different types of blood cell
99
What are the potential benefits of using stem cells for medicine!?
treating patients with currently untreatable conditions
growing organs for transplants
medical research
100
What are the 5 clinical issues to using stem cells for medicine!?
1.There is no guarantee of how successful these therapies will be, for example in the use of stem cells in healing damage caused by Parkinson's disease.
2.The difficulty in finding suitable stem cell donors.
3.The difficulty in obtaining and storing a patient's embryonic stem cells.
4.Mutations have been observed in stem cells cultured for a number of generations, and some mutated stem cells have been observed to behave like cancer cells.
5.Cultured stem cells could be contaminated with viruses which would be transferred to a patient.
101
What is a mutation!?
A random and spontaneous change in the structure of a gene, chromosome or number of chromosomes.
102
What are the 4 ethical issues to using stem cells for medicine!?
1.A source of embryonic stem cell is unused embryos produced by in vitro fertilisation.
2.For therapeutic cloning, is it right to create embryos for therapy, and destroy them in the process?
3.Embryos could come to be viewed as a commodity, and not as an embryo that could develop into a person.
4.At what stage of its development should an embryo be regarded as, and treated as, a person?
103
What are the 4 social issues to using stem cells in medicine!?
1.Educating the public about what stem cells can, and can't do, is important.
2.Whether the benefits of stem cell research use outweigh the objections.
3.Much of the research is being carried out by commercial clinics, so reported successes are not subject to peer review.
4.Patients could be exploited by paying for expensive treatments and being given false hope of a cure as stem cell therapies are only in their developmental stages.
104
What must be carefully controlled inside of our bodies for it to work effectively!?
The conditions inside of our bodies must be carefully controlled if the body is to function effectively
105
What are the row ways the conditions are controlled by!?
Chemical and nervous response
106
What do all control systems include!?
cells called receptors
the coordination centre
Effectors
107
What do receptors do!?
Detect stimuli
108
What is a receptor!?
Organs which recognise and respond to stimuli
109
What is a stimuli!?
Something that sets off a reaction in the nervous system, for example, light, heat, sound, gravity, smell, taste, or temperature. These changes in the environment are detected by receptors in an organism. The plural is stimuli.
110
What does the coordination centre do!?
receives and processes information from receptors around the body
111
List some examples of a coordination centre
The brain
Spinal chord
Pancreas
112
What is an effector!?
The organ, tissue or cell that produces a response.
113
What does an effector do to keep conditions correct!?
effectors bring about responses, which restore optimum levels, such as core body temperature and blood glucose levels
114
What is reaching optimum!?
The best or most appropriate - for instance, the conditions under which an enzyme works best (eg temperature and pH).
115
What are nerve cells called!?
Neurones
116
What do neurones do in the nervous system !?
. They carry an electrical message or impulse when stimulated.
117
What are a bundle of neurones called!?
A nerve
118
What are the 3 main types of neurones!?
sensory
motor
relay
119
What 2 features do the 3 neurones have in common!?
1.They have A long fibre (axon) which is insulated by a fatty (myelin) sheath. They are long so they can carry messages up and down the body
2.Tiny branches (dendrons) which branch further as dendrites at each end. These receive incoming impulses from other neurones.
120
What is the small gap called witch is found in between two neurones!?
A synapse
121
What is the definition of a synapse!?
A tiny gap at the junction between two nerve cells, which nerve signals must cross.
122
What happens at the synapse!?
Here the electrical signal must be converted into a chemical one, which is converted back to an electrical one on the other side of the synapse where the next neurone starts.
123
What is the first step of a neurone!?
an electrical impulse travels along the first axon
124
What is an axon!?
The long part of a nerve cell along which the electrical signal quickly moves.
125
What is the second step of a neurone!?
this triggers the nerve-ending of a neurone to release chemical messengers called neurotransmitters
126
What is a neurotransmitter!?
Chemical involved in passing nerve impulses from one nerve cell to the next across a synapse.
127
What is the 3rd step of a neurone!?
these chemicals diffuse across the synapse (the gap) and bind with receptor molecules on the membrane of the second neurone
128
What is the 4th step of a neurone!?
the receptor molecules on the second neurone bind only to the specific neurotransmitters released from the first neurone
129
What is the 5th step of a neurone!?
this stimulates the second neurone to transmit the electrical impulse.
130
What is the job of a receptor cell!?
Receptor cells detect a change in the environmental (a stimulus) and start electrical signals along neurons.
131
What happens to the electrical signals once a change in environment has been detected by the receptor cells!?
These move towards the central nervous system (CNS).
132
What is the CNC!?
Central nervous system
133
What is the role of the CNC!?
. The CNS is the brain and spinal cord. It coordinates the responses.
134
What happens after this “massage” has travelled through the CNC!?
Messages are then sent back along different neurones to muscles which contract or relax, and glands which secrete hormones
135
What are muscles and glands called in terms of the nervous system!?
Muscles and glands are called effectors.
136
Describe the journey once a change in environment has been recognised!?
Stimulus → receptor → coordinator → effector → response
137
What are receptors!?
Receptors are groups of specialised cells. They detect a change in the environment and stimulate electrical impulses in response
138
Where are receptors found!?
Sense organs contain groups of receptors that respond to specific stimuli.
139
Skin is a sense organ what is its stimulus!?
Touch and temperature
140
The tongue is a sense organ, what is its stimulus!?
Chemicals (in food and drink, for example)
141
The nose is a sense organ. What is its stimulus!?
Chemicals (in the air, for example)
142
The eye is a sense organ. What is its stimulus!?
Light
143
The ear is a sense organ. What is its stimulus!?
Sound
144
Muscles are effectors. What specific response does it have to a stimulus!?
a muscle contracting to move an arm
muscle squeezing saliva from the salivary gland
145
Glands are effectors. What specific response does it have to a stimulus!?
a gland releasing a hormone into the blood.
146
What is it called when there are different types of neurones working together!?
A reflex action
147
What is a reflex action!?
This is an automatic and rapid response to a stimulus, which minimises any damage to the body from potentially harmful conditions, such as touching something sharp or hot.
148
What is the sequence called that all reflex actions follow through the nervous system!?
A a reflex arch
149
What does a reflex arch not involve!? And how is this a positive!?
Crucially this does not involve the conscious part of the brain, which makes it much quicker. This in turn reduces damage to the body.
150
Describe the pathway of a reflex action…..
Stimulus —> receptor—>sensory neurone—> relay neurone —> motor neurone—> effector —>response
151
Why does the pathway of a reflex action initially not go through the brain!?
To speed up reactions
152
What is the first step of the reflex arch!?
A receptor in the skin detects a stimulus (the change in temperature).
153
What is the second step of the reflex arch!?
Sensory neurones send electrical impulses to relay neurones, which are located in the spinal cord. They connect sensory neurones to motor neurones.
154
What is the third step of a reflex arch!?
Motor neurones send electrical impulses to an effector
155
What is the 4th step of the reflex arch!?
The effector produces a response (muscle contracts to move hand away).
