What is mitosis + what is it for? x3

- Cell division and replication - Repair, Growth, reproduction

- Chromosomes condense and become visible - Membrane around the nucleus breaks down (in thier little pairs)

- Spindle fibres - Pull the chromatids to either side of the cell

- Changes/ mutations in cells - Cuase rapid and uncontrolable cell division

Topic 2- Cells and Control Flashcards by Artemis Buxton

What is mitosis + what is it for?

Cell division and replication
Repair, Growth, reproduction

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Where does Mitosis take place?

Nucleus

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What are the stages of a cell cycle?

-Interphase
-Prophase
-Metaphase
-Anophase
-Telophase
-Cytokinosis

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What occurs in interphase?

-Longest period of time
-Cell grows, replicates DNA
-Chemical reactions take place
-Creates new organelles e.g mitochondria/ ribosomes double

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What is Interphase?

And how much time to cells spend in it?

90%
Longest period of time
-Cell grows
-replicates DNA
-Chemical reactions take place
-Creates new organelles e.g mitochondria/ ribosomes double

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When does the membrane around the nucleus break down?

Late prophase

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What is Prophase?

Chromosomes condense and become visible
Membrane around the nucleus breaks down

(in thier little pairs)

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What is Metaphase?

-Chromosomes line up in the equator of the cell

One chromatid either side

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What is Anophase?

Spindle fibres
Pull the chromatids to either side of the cell

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What is Telophase?

-New membrane formed around chromasomes at each end of the cell

new nucleus

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What is Cytokinosis?

-The cell cytoplasm divides
-Leaving two genetically identical duaghter cells

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Why is mitosis important in growth, repair and
asexual reproduction?

Cells create new identical cells

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What is cancer?

Changes/ mutations in cells
Cuase rapid and uncontrolable cell division

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What are stem cells and why is differentiation important?

-Stem Cells divide and differentiate into specialised cells
-Need cells to perform different specialised functions

Muscle cells, nerve cells

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How do plants grow?

3 words

-Cell division
-Elongation
-Differentiation

By meristems, the tip

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Where does cell division take place in a plant?

-Tip
-Meristems

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What is elongation and where does it take place in plants?

Further back than meristems
Become longer

meristem cells produce auxins, cuase receptors to allow hydrogen into cells
Lowers pH, activates enzyme to break hydrogen bonds between cell wall
Allows flexibility for cell to change/ elongate0-

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Do plants or animals maintain embryonic stem cells all their life

Plants

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What are embryonic stem cells and where are they in animals?

Differentiate into any cell
Found in embryos

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Against/Risks associated with using embryonic stem cells

-Ethical (embryo, could be a human)
-Hard to come by (only embryo of animals)

-Catch a disease before implanted in body
-May become cancerouse (divide rapidly)
-Body may reject it (immune supressers used, more suseptible to disease)

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What stem cells in animals are not only found in the emrbyo for?

Differentiation into Blood
e.g White/red blood cells or plasma

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Where is the cerebellum?

The back of the head just above the spinal cord

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What is the cerebellum for?

-Balance
-Muscle coordination
-Music

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Where are the cerebral hemispheres?

Either side of the main part of the brain

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# x5 What do the cerebral hemisphere's do?

-Control opposite side of the bodies movements -Consciousness -Intelligence -Memory -Language

Where is the medulla oblongata?

-Bottom middle

What does the medulla oblongate control?

-Unconsious activity -Breathing rate -Heartrate -Blinking

How does a CT scanner work?

- X rays passed in all directions - Absorbed and transmitted by different parts of body -Produces image slices which are made into images by computers | Better at finding damaged areas

How does a PET scan work?

- Patien absorbs **radioactive** **glucose** - Emmits gamma rays **annihilation** - Areas that are used more (or cancerous) respire more and therefore absorb **more** of the **glucose** - Scan picks up which places emmit more gamma rays (being used more) | Better for discovering underlying activity

How does electrical stimulation of the brain work? | for reaserch

- Skull opened - Electrodes inserted (into the cerebral cortex) -Part of brain stimulated to see response of patient

Why is it diffuclt to treat damage in the **brain**?

-Hard to reach (encased in skull) -Has delicate surrounding brain tissue

Why is it diffuclt to treat damage in the **spinal cord**?

-No adult stem cells can differentiate -Hard to acces as protected by the spine

Why is it diffuclt to treat damage / **brain tumours**?

-Divide rapidly -Radio and chemo therapy can kill cancer cells but also harm healthy cells -*BLOOD BRAIN BARRIER* limmits drug delivery to the brain

What is a reflex arc?

nerve pathway for unconscious actions

What is the structure of a sensory neutron?

-Receptor Cell -Mylein sheeth covered axon -Cell body -Axon

What does a sensory neuron do?

Recieves stimuli (from outside body) and sends info to relay neurone

What does the dendtrites do?

Recieve information

What do axons do?

Transmit information

What is the axon terminal for?

-Transmit message to other cells

What does the **relay** neurone do

allow sensory and motor neurons to communicate

What is the Motor neurone's structure?

-Dendtrites attached to cell -Axon -Axon terminal

Where are synapses in a neurone?

-In between one neurones **axon** and the others **dendrite** -its a GAP -Neurones do not touch

What is are the two **neurones** that sandwich the synpase called?

Presynaptic Postsynaptic

How do synapses work in reflex arc?

2)Presynaptic release **neurotramsitters** (chemical messengers) 3) diffuses across synapse (20nm) 4) Binds with receptor in **postynaptic membrane** 5) Stimulates a new nerve impulse

What are the junctions between the synapse called?

synaptic cleft

*Where* is the **cornea** and what does it *do*?

-Transparent covering at front of eye -Directs light rays into the eye and helps it focus onto the retina

*Where* is the **lens** and what does it *do*?

-Behind the **iris** (middlish frontish) - Refracts light so it hits retina

*Where* is the **pupil** and what does it *do*?

-Black hole at front centre - Allows light into the eye

*Where* is the **iris** and what does it *do*?

-Behind the cornea infront of the lens -Controls pupil size

*Where* is the **cilary muscles** and what does it *do*?

- Attached to lens - Control lens shape

*Where* is the **retina** and what does it *do*?

-Back of eye, first layer -Contains **light receptors** -**Rods** detect light intensity -**Cones** detect colour/wavelength

*Where* is the **optic nerve** and what does it *do*?

-Back of eye (stem looking) -Sends impulses to the brain

*Where* are the **suspensory ligament** and what do they *do*?

-Between **lens** and **cilary** muscles -Fibres attach the two above

How much does the **cornea** refract for viewing ***near objects***?

Very little

How much does the **lens** refract for viewing ***near objects***?

More than cornea

How do we view near objects?

- Cilary muscles **contract** - Suspensory ligaments **relax** - **thick round lense**

How do we view far objects?

- Cilary muscles **relax** - Suspensory ligaments **contact** - **Flatter, longer lens**

What is **fovea** and its function?

-Small dent in retina -Has Cones

Do cones work better in light or dark?

light

What do cones do?

- Detect wavelength of light - The colour

What do rods do?

Detect light intensity | processed in black and white

How are rods and cones arranged?

-Cones in the centre -Rods more surrounding

What colours can the cones detect?

Green, Red, Blue

What is the virteous chamber

-Thick viscous -Maintains eye shape

How does the pupil change in bright light?

-Circular muscles **contract** -Radial muscles **relax** -Pupil becomes **smaller** | less light let in

How does the pupil change in darkness?

-Circular muscles **relax** -Radial muscles **contract** -Pupil enlargens | more light let in

What is cuases short sightedness?

-Light focused infront of retina -Eyeball is too long/cornea too curved

What is cuases long sightedness?

-Light focused behind of retina -Eyeball is too short/cornea too flat

How can short sight and long sight be fixed?

-Corrective lens -Eye surgery (cutting **cornea** to reshape it)

What type of lens for short sight?

-Concave (tree)

What type of lens for long sight?

Convex (oval)

What cuases cataracts

Protien build up

What do cataracts cuase

cloudy vision

How are cataracts fixed?

fualty lens replaced with plastic one

What cuases colour blindess?

-Genetic disorder -Passed by females (X chromosomes)

Why are men more likely to be colour blind?

- Girls need both X chromosomes to be fualty - Boys only need one X chromosome to be fualty | (XX) (XY)