Cells and Control

Biology.

What is a chromosome?

A wound up DNA molecule containing several genes

What shape is DNA?

Double Helix

What are the stages of the cell cycle?

Interphase, Prophase, Metaphase, Anaphase, Telophase ( + Cytokinesis)

What happens in interphase?

Cell grows, increases number of subcellular structures, cells duplicate

What happens in prophase?

Nucleus splits open, chromosome sister pairs condense and spread out through the cellWh

What happens in metaphase?

The chromosomes line up at the centre of the cell

What happens in anaphase?

The chromosomes are split up at the centromeres by spindle fibres and pulled to either side of the cell. The bundle of chromosomes at either side of the cell are identical

What happens in telophase and cytokinesis?

New nuclei form either side of the cell, the cell membrane and cytoplasm split into 2 new cells.

What are the purposes of mitosis?

Growth

Repair

Asexual reproduction

What are the three ways that organisms grow?

Cell division - more cells in the organism

Cell elongation - used in plants to increase the lengths of the shoots and roots and to follow tropisms

Cell differentiation - cells become adapted to their functions

What is a mutation?

Spontaneous change in a base of a DNA molecule

What is a tumour?

Lump of cells in the body as a result of a mutation causing cells to uncontrollably divide. Causes cancer when it begins to attack other cells

What is a percentile chart?

Compares the growth of a baby to the average growth patterns of many other babies to monitor normal or abnormal development

What is a stem cell?

A special cell capable of cell differentiation, where cells can become adapted to specific functions

Advantages of using stem cells to treat illness

Can be used to replace irreversible cell damages

Can be used to replace organs without the risk of rejectionD

Disadvantages of using stem cell therapy

Can cause cancer

Unethical, people think you killed someone for that

Recent technology, possible side effects are unknown

What is the nervous system?

A system of neurons which allow the body to communicate with parts of itself via electronic impulses. Allows reflexes

Receptor cells

Specialised cells which detect stimuli

What are effector cells

Muscle or gland cells which contract or secrete hormones when receiving electrical impulses.

What is the CNS

Central nervous system, consists of the brain and spinal cord

What is the PNS

Peripheral nervous system, sensory and motor neurons used to communicate between the CNS and receptor / effector cells

What are the cerebral cortex hemispheres?

2 halves of the brain which make up the majority of the brain. They control memory, personality, and most cognitive abilities

What is the cerebellum

Section of the brain in the lower back. Controls fine motor movement and muscle coordination, balance and posture

What is the medulla oblangata?

Connects the brain to the spinal cord, controls involuntary reflexes such as breathing and heart rates.

Issues with brain treatments

Brain is hard to access due to the skull. The meninges and blood brain barrier also make it harder to penetrate the brain due to their delicacy. The brain is also made up of sensitive neurons which mean that small faults in brain surgery lead to permanent disability. Some tumours and bleeds are therefore inaccessible from the outside

What is a CT scan?

A scanner that uses X - rays to build 2D monochrome images of the brain. Shows bleeds and tumours indicated by the normally brightly glowing spots or degeneration where it is exceptionally dark.

How does a PET scanner work?

Uses a ring of detectors and beta+ emissions to build a 3D image of the brain. Can also indicate brain activity and a lack of it.

What are the steps of the reflex arc?

Stimulus - a change in environment

Receptor cells - detect the stimuli

Sensory neurons - transmit the electrical impulse to the CNS in relay neurons

Relay neurons - send impulses to the motor neurons

Motor neurons - neurons which send the impulses to the effector cells

Effector cells - muscle or gland cells which will secrete substances or contract to protect the organism from harm.

What happens across a synapse?

The electrical impulse arrives at the presynaptic neuron

Neurotransmitter diffuses across the synapse

Neurotransmitter binds at the postsynaptic neuron

Electrical impulse reforms

Happens on either side of the relay neuron, from sensory to relay, then relay to motor.

What does the cornea do?

Protective layer around the eye, which also refracts light entering it

What does the lens do?

Transparent disc in the eye which gets shorter or longer to accommodate closer or further objects.

What does the retina do?

Layer of receptor cells (rod and cones) which detect light intensity, allow you to see when light is low, and detect light colour with RGB cones.

What does the iris do?

Coloured part of the eye which contracts or relaxes to dilate or constrict the pupils, when less or more light enters the eye respectively.

What is a cataract?

Protein buildup in the lens. Causes cloudy vision. Corrected via lens replacement surgery.What

What is colour blindness?

A disease which affects the cone cells and the ability to detect light colour. Has no treatments or cure as of today.