Topic 2 - Cells and Control Flashcards
What formation is DNA found in?
A double helix formation
What are sections of DNA called?
Genes
What are the six stages of mitosis?
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
What are the three things that happen during interphase?
- Replicate DNA
- Grow in size
- Increase number of sub-cellular structures
What happens during prophase?
DNA condenses and chromosomes become visible
What happens during metaphase?
Chromosomes line up in the middle of the cell
What happens during anophase?
A copy of each chromosome is pulled to opposite ends
What happens during telophase?
New membranes form around chromosomes at each end
What happens during cytokenisis?
Cell membrane divides forming two identical daughter cells
What is cancer and how’s it formed?
A non-communicable disease which is formed by uncontrolled mitosis of cells
What are the two types of cancer tumours?
Malignant
Benign
What are the characteristics of a malignant cancer tumour?
They are cancerous, fast growing and can break off and spread to other parts of the body
What are the characteristics of benign cancer tumours?
Slow growing and non-cancerous as they cannot spread throughout the body
What is one risk factor for cancer and why? (hint: 🫃)
Obesity as fat can cause cells to divide
What is the process of differentiation?
Cells become specialised where different genes are turned on and off in each cell to change their shape and sub-cellular structures to become specific to certain functions
What are stem cells?
Undifferentiated cells that can produce different cell types through differentiation
What are the 3 stem cells you need to know?
Embryonic stem cells
Adult stem cells
Meristem cells
What cells can embryonic stem cells differentiate into?
Almost any type of animal cell
Where are adult stem cells found and what cells can they differentiate into?
Bone marrow and can differentiate into some types of animal cells
Where are meristems found and what cells can they differentiate into?
Tips of roots and shoots and can differentiate into any type of plant cell
What are issues are related with the use of embryonic stem cells?
Unused embryo’s will be destroyed and there is risk of viral infection
What is the main benefit of using stem cells to treat patients?
There is little to no chance of the cells being rejected by the immune system
What are the 5 main parts of the brain?
Cerebral cortex
Cerebellum
Medulla oblongata
Hypothalamus
Pituitary gland
What does the cerebral cortex control?
Language, memory, intelligence
What does the cerebellum control?
Muscle contractions and balance
What does the medulla oblongata control?
Unconscious actions like breathing
What are 2 issues with treating the brain?
Very delicate organ so can be easily damaged and very hard to access and repair after surgery
What are the two types of scans that can be used for the brain?
PET scans
CT scans
How do CT scans work and what does it show?
They use x-rays to produce an image of the brain showing the main structures
How do PET scans work and what does it show?
They use radioactive chemicals to show which parts of the brain are active and they show more precise structures and their functions
What are the 7 stages of the nervous system in order?
- Stimulus
- Receptor
- Sensory neuron
- CNS
- Motor neuron
- Effector
- Response
What is a stimulus?
A change in the environment
What do receptors do?
Cells that detect the stimulus and convert it into an electrical impulse which is sent along sensory neurones to the CNS
What does the CNS do?
It coordinates a response to the stimulus and sends information to the effector along a motor neurone.
What do impulses travel through the CNS along?
Relay neurones
What does the effector do?
It responds according to the information given by the CNS which could be a muscle contraction
What is reaction time?
The amount of time it takes to respond to a stimulus
What are the three types of neurones?
Sensory neurone
Motor neurone
Relay neurone
What happens at a sensory neurone?
Long dendron carries impulses from receptors to the cell body located in the middle of the neurone, short axon carries impulse from cell body to CNS
What happens at a motor neurone?
Short dendrites carry impulses from CNS to cell body, long axon carries impulse from CNS to effector cells
What happens at a relay neurone?
Short dendrites carry impulses from sensory neurone to cell body, axon carries impulses from cell body to motor neurones
What is a synapse?
A connection/gap between two neurones
What are the two stages for an impulse/signal to travel across a synapse?
1.Impulse is transferred by neurotransmitters which diffuse across the gap
2. Neurotransmitters set off the signal in the next neurone
What are the 6 stages of a reflex?
- Stimulus happens
- Pain receptor is stimulated
- Impulse travels along sensory neurone
- Impulse passed along relay neurone, via a synapse
- Impulse travels along motor neurone, via a synapse
- Impulse reaches the effector and it the response happens
What is a positive of reflexes?
They happen faster than normal responses as you don’t have any time to think
What are the 8 structures in the eye?
Iris
Cornea
Pupil
Lens
Ciliary muscle
Suspensory ligament
Retina
Optic nerve
What are the two structures within the retina?
Rods and cones
What is the difference between rods and cones?
Rods are more sensitive in dim light and cones are more sensitive to colour
What does the cornea do?
It refracts to bend light into the eye
What does the iris do?
Controls how much light enters the eye by contracting and relaxing
What does the lens do?
Refracts light onto the retina
What does the optic nerve do?
Carries electrical impulses from receptors to the brain
What happens to the eye when looking at distant objects?
The ciliary muscle relaxes allowing the suspensory ligaments to pull tight so less light is refracted
what happens to the eye when looking at close objects?
The ciliary muscle contracts which allows the suspensory muscle to relax so light is refracted more
What are long-sighted people not able to focus on nearby objects?
This is because the lens is the wrong shape and doesn’t bend light enough so light is brought into focus behind the retina
Why are short-sighted people not able to focus on distant objects?
This is because the lens is the wrong shape and bends too much light so light is brought into focus in front of the retina
What contact lens can be used to correct long-sightedness?
Convex lens
What contact lens can be used to correct short-sightedness?
Concave lens
What is colour-blindness caused by?
It is where the coloured cones like red or green in the retina are not working properly
What is a cataract and what does it lead to?
A cloudy patch on the lens of the eye which stops light from being able to enter the eye normally leading to blurred vision
How can a cataract be treated?
By replacing the faulty lens with an artificial lens
