Cells And Control Flashcards
What is mitosis?
Mitosis is a type of cell division which produces two genetically identical daughter diploid cells.
Describe the stage of interphase
The cell grows and subcellular structures like mitochondria and ribosomes multiply. The chromosomes copy itself to get ready to undergo mitosis.
Describe the stages of mitosis
Prophase - DNA condenses, chromosomes become visible and nuclear membrane breaks down.
Metaphase - Chromosomes line up along the equator of the cell.
Anaphase - Spindle fibres attach to the chromosomes. Chromosomes are pulled to opposite ends of the cell.
Telophase - Nucleus divides and a new membrane forms around each chromosome.
Cytokinesis - The cell’s cytoplasm and membrane divides and produces two genetically identical diploid daughter cells.
What is mitosis important for? (3)
Growth, To repair damaged cells, Asexual reproduction
How does a cell become cancerous?
This is when a cell divides uncontrollably, leading to the formation of a tumour.
How does growth occur in animals?
Growth occurs via mitosis and cell differentiation.
Describe growth in plants
Growth occurs through cell division, cell differentiation and cell elongation, controlled by auxins.
What are percentile charts used for?
To monitor growth, by using measurements like head circumference and length.
They help doctors determine if growth is normal, slower, faster or irregular.
What is a stem cell?
A stem cell is an undifferentiated cell capable of dividing to produce more similar cells.
What are embryonic stem cells?
They form when an egg and sperm fuse together to form a zygote.
They can differentiate into any type of cell in the body.
What are adult stem cells?
Found in bone marrow and can form various types of cells, including blood cells.
What are meristems in plants?
Found in root and shoot tips, capable of differentiating into any type of plant cell throughout the plants life.
What is therapeutic cloning?
Therapeutic cloning involves producing an embryo with the same genes as the patient.
What are the benefits of stem cell research?(3)
- Can be used to replace damaged or diseased body parts.
- Unwanted embryos from fertility clinics could be used as they would otherwise be discarded.
- Research into the process of differentiation
What are the problems of stem cell research? (3)
- We do not completely understand the process of differentiation, so it is hard to control stem cells to form the cells we desire.
- People may have religious or ethical objection as it is seen as interference with the natural process of reproduction.
- If the growing stem cells are contaminated with a virus, an infection can be transferred to the individual.
What is the CNS?
The CNS consists of the brain and spinal cord.
What is the Cerebrum responsible for?
Responsible for consciousness, memory, intelligence and visual and sensory processing.
What is the Cerebellum responsible for?
Responsible for controlling muscle movements and coordination.
What is the Medulla oblongata responsible for?
Responsible for breathing, digestion, swallowing and sneezing.
How do CT scans and PET scans differ in imaging the brain?
CT scans use x-ray radiation from multiple angles to create 3D image, useful for examining bleeding and damage.
PET scans use a radioactive tracer to highlight areas of increased blood flow, helpful in identifying cancerous tumours.
Why is investigating the brain’s functions and treating brain damage challenging? (3)
- It is complex, delicate and can easily be damaged.
- Drugs given to treat diseases cannot always reach the brain because of the membranes that surround it.
- It is not fully understood which part of the brain does what.
Describe the pathway of the nervous system
The receptors convert the stimulus into electrical impulses, which travel along sensory neurones to the CNS. The CNS coordinates a response, sending impulses along motor neurones to effectors, resulting in a response (contracting a muscle or glands secreting hormones).
How does the reflex arc differ from the nervous system pathway?
An involuntary response, does not involve the brain used to keep the body out of danger.
1. The receptors convert the stimulus into electrical impulses, which travel along sensory neurones to the CNS. 2. In the CNS, the impulses travel to the relay neurones. 3. Impulses are then sent along a motor neuron, resulting in a response (contracting a muscle or glands secreting hormones).
What are synapses and how do they function?
Synapses are the gaps between two neurones.
When the impulse reaches the end of the first neuron, a chemical called neurotransmitters is released into the synapse. This neurotransmitter diffuses across the synapse. When the neurotransmitter reaches the second neurone, it triggers the impulse to begin again in the next neurone.
What is the function of the myelin sheath?
Myelin sheaths are insulating layers around the axon which causes the electrical impulses to travel faster.
Describe the structure and function of the Retina
Contains rod and cone cells.
Rod cells - responsible for light intensity
Cone cells - responsible for colour vision
Explain the functions of the cornea, iris and lens
The cornea allows light into the eye, iris controls the pupil size and the lens focuses light onto the retina.
What are some common eye defects and how are they treated? (4)
Short sightedness - treated with concave lens
Long sightedness - treated with convex lens
Cataracts - treated with lens replacement surgery
Colour blindness - usually genetic and untreatable
