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9 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Stages of Mitosis |
INTERPHASE- Before cells divides, cell has to grow to increase the amount of sub cellular structures. The it has to duplicate its DNA so there’s one copy for each new cell. The DNA forms an x shape. PROPHASE- chromosomes condense getting shorter and fatter. Membrane around nucleus breaks down and chromosomes lie free in cytoplasm METAPHASE- chromosomes line up ad the centre of the cell ANAPHASE- spindle fibres pull chromosomes apart TELOPHASE- membranes form around each set of chromosomes. These become the nuclei of the two new cells Before telophase ends, the cytoplasm and cell membrane divide to form separate cells, process called cytokinesis |
I Peas Make Awful Tarts C |
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Cell division and growth |
Plants and animals grow due to: 1) cell differentiation (when cells specialise) 2) cell division (by mitosis). Plants also grow by cell elongation (the cell gets bigger). Plants always differentiate but animals stop after a very early stage. Cancer is the cause of uncontrolled cell division. As mitosis is controlled by the genes, a change in one of the genes that controls mitosis can cause cells to divide uncontrollably. Percentile graphs monitor growth |
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Stem cells |
Undifferentiated cells are called stem cells. They can divide by mitosis and become new cells that can then differentiate. Stem cells are found in early human embryos. This means stem cells are really important for the growth and development of organisms. Adults have stem cells but are only found in certain places such as bone marrow and are not as versatile as embryonic stem cells. In plants, the only cells that divide by mitosis at found in plant tissue call meristems, which is found in the areas of a plant which is growing. Meristem produce unspecialised cells that are bake to divide and form any cell type. Stem cells can be used in medicine, and can cure diseases such as sickle cell anemia. This is done by extracting stem cells from very early human embryos and growing them. However there are some risks: 1) tumour development, cells divide uncontrollably. 2) disease transmission, if sonar is infected with disease, the virus can be passed in as virus lives inside cells. 3)rejection, of stem cells not grown using the patients own stem cells, patients body may recognise cells as foreign, immune system will be triggered and cells killed. Drugs can be used but makes patient susceptible to diseases. |
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The brain and spinal cord |
Parts of the brain: CEREBRUM- right hemisphere: in charge of muscles on left side. Vice versa. Different parts control different things including movement, intelligence, memory, language and vision. CEREBELLUM-responsible for muscle coordination and balance. MEDULLA OBLONGATA- controls unconscious activities like breathing and heart rate. Types of scanner used to investigate brain function: CT SCANNING- used to X-ray brain to produce image of brain. Shows main structure of brain but not function. PET SCANNING- use radioactive chemicals to show which parts of the brain is active. Very detailed and shows structure and function of brain in real time. Can show active and inactive areas so useful for studying disorders. Problems with fixing nervous system: 1) hard to repair damage as the CNS (Central Nervous System) doesn’t readily repair and scientists haven’t found it how to repair nervous tissue. 2) hard to access and treat. 3) treatment for problems may lead to problems damage as operations can cause further damage. |
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The Nervous System |
The CNS coordinated a response. Stimulus happens. Receptor detects stimulus and info is converted to a revois (electrical) impulse. This is sent along sensory neurones to the CNS (brain and spinal cord). CNS coordinates response. Response travels through the CNS along a relay neurone. Info sent to an effector (muscle or gland) along a motor neurone. The time taken to respond to a stimulus is called your reaction time. Dendrites and fendrons carry nerve impulses towards the cel body. Axons carry implies away from the cell body. Both are extensions that connect to other neurones. |
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Types of neurones |
SENSORY NEURONE: carries nerve impulses from receptor cells to the cell body, which is in middle of neurone. MOTOR NEURONE: many short dendrites carry nerve impulses from the CNS (Central Nervous System) to the cell body. One long axon carriers nerve impulses from the cell body to effector. RELAY NEURONE: many short dendrites carry nerve impulses from sensory neurones to the cell body. An axon carries nerve impulses from the cell body to motor neurones. Sensory, relay , motor |
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Synapses and reflexes |
The connection between 2 neurones is called synapses. The nerve signal is transferred by chemicals called neurotransmitters, which diffuse across the gap. The neurotransmitters then set off a new electrical signal in the next neurone. The transmission of a nervous impulse is very fast, but it is slowed down a cut after the synapse because the diffusion of neurotransmitters across the gap time. REFLEXES: are automatic rapid responses that go brought spinal cord or unconscious part of the brain. Stimulus is detected by receptors, impulse sent along a sensory neurones to a relay neurone in the CNS. When the impulses reach a synapse between the sensory neurone and the relay neurone they trigger neurotransmitters to be released. These cause impulses to be sent along the relay neurone. When impulses reach a synapse between the relay neurone and motor neurone same thing happens. Neurotransmitters are released and cause impulses to be sent along the motor neurone. The impulses then travel along the motor neurone to the effector. A reflex helps protect the eye. Light receptors in the eye detect bright light and send a message along a sensory neurone to the brain. The message then travels along a relay neurone to a motor neurone, which tells circular muscles in the iris to contract making the pupil smaller. |
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Parts of the eye |
CORNEA reflects light into the eye IRIS controls how much light enters the pupil LENS refracts light, focusing it onto the retina RETINA is the light sensitive part covered in receptor cells called rods and cones which detect light RODS are more sensitive in dim light but can’t sense colour CONES are more sensitive to different colours but a not so good in dim light OPTIC NERVE. Information from light in converted into electrical impulses. Optic nerve carried these impulses from the receptors to the brain. |
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Long and short sightedness. Colour blindness and cataracts |
To look at distant objects the ciliary muscles relax which allows the suspensory ligaments to pull tight. This pulls lens into a left rounded shape so light refracts less for close objects, vice versa. LONGSIGHTED: unable to focus on near objects. Lens doesn’t bend light enough so convex lens needed. SHORT SIGHTED: unable to focus on distant objects. Lens bend light to much so concave lens is needed. Colour blindness is caused when cones in the retina doesn’t work. No cure. A cataract is a cloudy patch in lens which stops light entering the eye normally. People with cataracts are likely to have blurred vision. Colours may look less vivid and have difficulty seeing in bright light. Cataract can be treated by replacing lens for an artificial one. |
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