Cells and Control Flashcards
Which phase does a cell stay for the longest during mitosis?
Interphase
What are the stages of mitosis, in order?
Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
Where does mitosis happen?
In any cells apart from gametes (sex cells)
What is the name of the cell that divides and its divided products?
Parent cell, daughter cells (which are identical to the parent cell)
What happens in the interphase?
- DNA of chromosome duplicates to form 2 chromatids
- Chromosomes now condensed and visible
What happens in the prophase?
- Nuclear membrane starts to disappear
- Spindle fibres appear
What happens in the metaphase?
- Chromosomes line up on spindle fibres on equator
- Nuclear membrane now completely gone
What happens in the anaphase?
- Chromatids are separated as are pulled to opposite poles of cell on spindle fibres
- Each pole now a chromosome
What happens in the telophase?
-Membrane forms around each set of chromosomes to form nuclei
What happens in cytokinesis?
- Cytoplasm of cell is separated as cell membranes form around each of them into 2 daughter cells
- Cell walls form in plant cells
What is an anagram to remember the stages of mitosis?
I Promised My Aunt To Camp
What is the name of the group of cells (plant tissue) near the end of each shoot and roots which allow plants to continue growing throughout their lives?
Meristems
What is differentiation?
The process in which changes less specialised cells into more specialised ones to perform a particular function
What is the function of a xylem vessel?
It carries water and dissolved mineral salts up the plant
How is a root hair cell different from other types of root cell and how is it adapted to its function?
It has a long extension into the soil; this increases the surface area, which helps absorb water and mineral salts
How is the palisade cell adapted to its function?
- It has many more chloroplasts in it than other cells, as they are the main site of photosynthesis
- Have vacuoles that restrict the chloroplasts to remain on a layer near the outside of the cell where they can be reached by light more easily for photosynthesis
What is mitosis used for?
Growth, repair and asexual reproduction
What happens if cells divide uncontrollably from mitosis?
They form a lump of cells called a tumour, which is worse if these are cancer cells
How do plant cells grow by enlarging after mitosis?
Young plant cells have small vacuoles which take in water by osmosis and enlarge
How is the growth of babies checked by percentile charts?
By measuring their length/height, head circumference and their weight
What are stem cells?
Unspecialised cells that can develop into any type of cell, such as early embryos
What happens after the 8 cell stage in embryonic stem cells?
Most of the embryonic cells become specialised and can no longer differentiate. Some will become never, blood, muscle, bone cells, etc
What is the difference between adult stem cells and embryonic stem cells?
Adult stem cells can only make a small number of cell types
What are some uses of embryonic stem cells?
- Replacing or repairing brain cells to treat people with Parkinson’s disease
- Replacing damaged cells in the retina in the eye to treat some kinds of blindness
- Growing new tissues in the lab to use for transplants or drug testing
What are some uses of adult stem cells?
- Treatment of leukaemia
- Potentially growing new tissues to match to the patient
What are advantages and disadvantages of using embryonic stem cells?
-Easy to extract and produces most types of cells
BUT
-Embryo is destroyed when cells are removed and so some think they have a right to live (unethical)
What are advantages and disadvantages of using adult stem cells?
-No embryo destroyed (not ethical issue) and if taken from the person to be treated, will not cause rejection by the body
BUT
-Only produces a few types of cell
What are advantages and disadvantages of all stem cells?
-Replaces faulty cells with healthy cells so person is well again
BUT
-There is a risk as some stem cells may not stop dividing, and so cause cancer from tumours
What are neurones and what do they do?
Nerve cells - process information and control the body
What is the cerebral cortex?
- Makes up 80% of the brain (the most important part)
- Controls and processes body and information
- Controls personality, our senses, language memory, behaviour and consciousness
What does the cerebellum control?
Balance and posture
What is the medulla oblongata?
Controls your heart rate, your breathing rate and reflexes such as vomiting, swallowing and sneezing
What does the medulla oblongata connect?
The brain to the spinal cord
How does a CT scan to develop an image of the structures in the brain work?
- X-ray beam moves in a circle around the head
- Detectors measure the absorption of the X-rays
- Computer uses this info to build up a view of the inside of the body as a series of ‘slices’
What does damage to the spinal cord do?
Reduces the flow of info between the brain and parts of the body
Why can’t stem cells be used to repair the damage caused by a spinal injury?
There are no adult stem cells that can differentiate into neurones in the spinal cord, and so new neurones can’t be made to repair the damage
How can you remove a tumour?
Cut it out or the cells can be killed using radiotherapy and chemo
What does the central nervous system (CNS) do?
Control your body using electrical signals called impulses
What are the organs in the CNS?
The brain, the spinal cord and sensory organs
What is a stimulus?
Anything your body is sensitive to, including changes in your body and in your surroundings
What do receptor cells do?
Detect stimuli
What is neurotransmission?
The travelling or transmission of impulse; it happens in neurones (nerve cells)
What are effectors?
Things that carry out actions, such as muscles and glands (eg. sweat glands)
What do synapses do to the speed of neurotransmission?
Slow it down; synapses is the point where 2 neurones meet
What are reflex actions?
Responses that are automatic, extremely quick and protect the body
What do reflex arcs do?
They bypass the parts of the brain involved in processing info and so are quicker than responses that need processing
What are neurones?
Specialised cells that carry nervous impulses
What are the 3 main types of neurones?
Sensory, motor and relay
What are the 3 main structures in a neurone?
Axon, dendrite and myelin sheath
What is the function of the axon?
Carries impulses away from the cell body
What is the function of the dendrite?
Receives impulses from other neurones
What is the function of the myelin sheath?
It is a fatty layer that provides electrical insulation around the neurone
What do sensory neurones do?
They carry impulses from receptors to the CNS
What is the eye?
A sensory receptor that detects light and sends impulses along sensory neurones to the brain
What do the cornea and the lens do?
They focus the light to form a sharp image on the retina
What does the retina contain that helps it detect light and form an image?
Receptor cells called rods and cones
What does the iris do?
It is a ring of muscle that controls the size of the pupil
What does your eye do when you focus on a near object?
- Ciliary muscle contract
- Suspensory ligaments become slack
- Lens becomes rounded
- Image focused on the retina
When do cataracts occur?
When the lens goes cloudy (opacity = cloud formation); as a result, light can’t get through it properly
What happens in colour blindness?
Normal eye - 3 types of cone cell that detects red, green and blue light
Colour blindness - when at least 1 type of cone cell is missing or does not work properly
Describe the steps of laser eye surgery
- Anesthetic drop on eye
- Create flap
- Laser reshapes
- Close flap
- Eye heals itself
What is astigmatism?
Usually caused by an imperfectly shaped cornea which causes the light to be refracted by different amounts in different planes
