2) Cells and Control Flashcards by William Odgers

What is mitosis used for?

Growth
Repair
Asexual reproduction of cells

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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

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What happens in mitosis?

The two sets of chromosomes are pulled to opposite ends of the cell
Then the nucelus divides in two

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What is cytokinesis?

The cytoplasm and cell membrane divide to create two idential diploid cells

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What are the stages of mitosis?

(Interphase)

Prophase
Metaphase
Anaphase
Telophase

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What happens during prophase?

Chromosomes condense (coil up tightly)

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What happens during metaphase?

Chromosomes line-up along the middle of the cell

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What happens during anaphase?

The two sets of chromsomes are pulled to opposite ends of the cell

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What happens during telophase?

The nucelus splits and two nuclei form

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What does mitosis ensure?

Both daughter cells have the same chromosomes as each other and the parent cell

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Why are identical chromosomes important in mitosis?

Processes require identical cells (growth and repair of tissues)

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What are the types of tumour?

Malignant (harmful)

Benign (harmless)

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What is cancer?

Uncontrolled division of cells

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What do malignant tumours do?

Invade neighbouring tissues and spread through the blood

Creating secondary tumours

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What do benign tumours do?

Stay in a specific part of the body

Often within a membrane

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In plants what regions can growth happen in?

Zone of cell division
Zone of elongation
Zone of differentiation

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What happens in the zone of cell division?

Cells divide by mitosis and new cells are created

Near the tip of a root

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What happens in the zone of elongation?

New cells grow in size

Further up the root

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What happens in the zone of differentiation?

New cells differentiate

Even further up the root

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What is babies growth shown by?

Percentiles charts
age (x-axis)
weight (y-axis)

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What is cell differentiation?

The process where a cell develops new sub-cellular features to let it perform a specific function

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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

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When can cell differentiation happen in plants?

Their whole life plants are able to create new tissues

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Why does cell differentiation occur ina dult animals?

To replace cells and repair tissues

This is rare

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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