2) Cells and Control Flashcards
What is mitosis used for?
Growth
Repair
Asexual reproduction of cells
What is interphase?
The initial growth phase: extra ribosomes, mitcohondria and sub-cellular structures produced
Cell’s chromosomes replicated so there are two sets of the cell’s chromosomes
What happens in mitosis?
The two sets of chromosomes are pulled to opposite ends of the cell
Then the nucelus divides in two
What is cytokinesis?
The cytoplasm and cell membrane divide to create two idential diploid cells
What are the stages of mitosis?
(Interphase)
Prophase
Metaphase
Anaphase
Telophase
What happens during prophase?
Chromosomes condense (coil up tightly)
What happens during metaphase?
Chromosomes line-up along the middle of the cell
What happens during anaphase?
The two sets of chromsomes are pulled to opposite ends of the cell
What happens during telophase?
The nucelus splits and two nuclei form
What does mitosis ensure?
Both daughter cells have the same chromosomes as each other and the parent cell
Why are identical chromosomes important in mitosis?
Processes require identical cells (growth and repair of tissues)
What are the types of tumour?
Malignant (harmful)
Benign (harmless)
What is cancer?
Uncontrolled division of cells
What do malignant tumours do?
Invade neighbouring tissues and spread through the blood
Creating secondary tumours
What do benign tumours do?
Stay in a specific part of the body
Often within a membrane
In plants what regions can growth happen in?
Zone of cell division
Zone of elongation
Zone of differentiation
What happens in the zone of cell division?
Cells divide by mitosis and new cells are created
Near the tip of a root
What happens in the zone of elongation?
New cells grow in size
Further up the root
What happens in the zone of differentiation?
New cells differentiate
Even further up the root
What is babies growth shown by?
Percentiles charts
age (x-axis)
weight (y-axis)
What is cell differentiation?
The process where a cell develops new sub-cellular features to let it perform a specific function
When does cell differentiation usually occur?
During an organism’s development
Cells divide to form embroys that differentiate to produce cells that can perform the body’s functions
When can cell differentiation happen in plants?
Their whole life plants are able to create new tissues
Why does cell differentiation occur ina dult animals?
To replace cells and repair tissues
This is rare
What are stem cells?
Undifferentiated cells
Where are stem cells found?
Plant meristems
Embryos
Bone marrow
What are stem cell uses?
Therapeutic cloning
Stem cell treatments
How are stem cells used in stem cell treatments?
They may replace damaged cells that cause diabates or paralysis
Also burns, arthritis, Parkinson’s
What is therapeutic cloning?
A process that produces an embryo with the same genes are the patient
This prevents rejection of cells
What are disadvantages of stem cells?
Viral infections
Ethical beliefs
Rejection
What are ethical beliefs against stem cell?
Belief life begins at contrcaeption (embryo is alive)
View use of embryonic stem cells as killing an embryo
What are the components of the human nervous system?
Brain
Spinal cord
Neurones (nerve cells)
Effectors
What are nerve cells also know as?
Neurones
What do neurones carry?
Electrical impulses
What are synapses?
Gaps between neurones
What chemical is released at synpases?
Neurotransmitters
How do neurotransmitters move across a synpase?
They diffuse
What do neurotransmitters bind to at the next neurone?
Recpetors
What does the presence of neurotransmitters cause to be produced?
An electrical impulse at the next neurone
What do axons do?
Carry electrical impulses away from the cell body
What do dendirtes do?
Carry electrical impulses towards the cell body
What are axons carried in?
A myelin sheath which inslates the neurone so electrical impulses travel quicker
What is the CNS made up of?
Neurones (nerve cells)
Spinal Cord
Brain
What are the components of a reflex arc?
Stimulus Receptor Neurones Effector Response
What are the 3 types of neurone?
Sensory
Relay
Motor
What does the sensory neurone do?
Carries the signal in the form an electrical impulse to the CNS
What does the relay neurone do?
Relays the electrical impulse from the sensory neurone to the appropriate motor neurone
Where is the relay neurone found?
The CNS
What does the motor neurone do?
Carries the electrical impulse from the CNS to an effector
What is the brain made up of?
Millions of interconnecting neurones
What are the 3 parts of the brain?
Cerebral hemispheres
Cerebellum
Medulla oblongata
What is the medulla oblongata responsible for?
Unconscious activites (breathing, heart rate)
What is the cerebellum responsible for?
Muscle coordination (movement, posture, balance, sseech)
What are the cerebral hemispheres responsible for?
Conscious thought (memory, language, intelligence)
What is CT scanning?
Taking an x-ray of the brain and building a 3D image to look for tumours
What do PET scans do?
Look at how parts of the brain function
How do PET scans work?
Using radioactive glucose the amount of glucose different parts of the brain are using up can be detected
Why is damage to neurones often permanent and irreversible?
Neurones cannot be replaced like other cells
What do brain tumours show up as on CT scans?
White blotches
What are the parts of an eye?
Cornea Sclera Retina Pupil Iris Ciliary muscles Suspensory ligaments Optic nerve
What is the sclera?
The opaque protective white of the eye
What is the cornea?
The transparent frontal part of the eye that refracts light
What is the retina full of?
Receptor cells
Sensitive to brightness and colour
What does the optic nerve do?
Transmits visual information from the retina to the brain
What is the pupil?
The hole in the centre of the iris which light passes through to get to the retina
What does the iris control?
Pupil diameter and therefore the quantity of light reaching the retina
What are suspensory ligaments?
A ring of fibres that connect ciliary muscles to the lens
What are ciliary muscles?
A ring of smooth muscles that can change the shape of the lens which the eye uses to focus light
What happens when focusing on a close object?
Ciliary muscles contract
Suspensory ligaments loosen
Lens becomes trhicker and rounder
What does a thick round lens do to light rays?
Significant refract
What happens when focusing on a distant object?
Ciliary muscles relax
Suspensory ligaments tighten
Lens becomes flatter and thinner
What does a flat thin lens do to light rays?
Minor refraction
What happens to pupil size when there is too much light?
Smaller pupil
What happens to pupil size when there is not enough light?
Bigger pupil
What is the process of changing the lens shape in order to focus on an object?
Accomodation
When does short-sightedness happen?
When rays of light focus in front of the retina
When does long-sightedness happen?
When rays of light focus behind the retina
What eye defect is an inherited condition?
Colour blindness
What causes colour blindness?
Defects in cone cells
What do cone cells do?
Detect light colour
What do rod cells do?
Detect light intensity
What are photoreceptors?
Light-sensitive cells in the retina
Rod cells
Cone cells
What causes cataracts?
A build-up of protein on the lens making the pupil cloudy
Where can synapses be found?
Each junction of a reflex arc
What are the cerebral hemispheres also know as?
Cerebral cortex
What do the ciliary muscles and suspensory ligaments change the shape of?
The lens
