Topic 2 Cells and Control Flashcards
Interphase (not actually mitosis)
DNA spread out in long string
Cell grows and increases amount of sub cellular structures
Duplicates DNA into X shaped chromosomes (each arm is exact copy)
Prophase
Chromosomes condense and become short and fat
Nucleus membrane breaks down and chromosomes lie free in cytoplasm
Cell fibres start to form
Metaphase
Chromosomes line up in middle of cell
Anaphase
Cell fibres pull chromosomes apart
Each arm of chromosomes go to opposite end of cell
Telophase
Membranes form around each sets of chromosomes that become nuclei of two new cells
Cytokinesis
Cytoplasm and cell membrane divide to form two, genetically identical daughter cells
Uses of mitosis
To grow or replace damaged cells
Use mitosis to reproduce (asexual reproduction) like strawberry plants
Growth
Increase in size or mass
Growth in animals
Happens by cell division
Grows when young and stop growing at full growth
Most cell division happens for repair at full growth
Cell differentiation lost at early age
What is a tumour?
Damages or changes in cell’s DNA that result in uncontrolled cell division that creates a mass of abnormal cells
Growth in plants
Happens by cell elongation
Cell division happens in meristems (tops of roots and shoots, contain stem cells)
Continue to differentiate throughout whole life
When is a tumour considered a cancer?
When it starts to invade and destroy nearby cells
What does 50th percentile line represent mean?
Shows the mass that 50% of babies will have reached at a certain age
When a doctor might be concerned with a child’s growth?
When it moves up or down 2 percentile lines or more, is above the top percentile line or below the bottom percentile
When there is an inconsistent pattern (small baby with large head)
3 measurements taken on percentile charts for babies
Weight, height and head circumference
Where are stem cells found
In early human embryos - embryonic stem cell
In adults in bone marrow - adult stem cell
Difference between adult and embryonic stem cell
Embryonic stem cells can become any specialised cell in the body but adult stem cells can only become some
Advantages of stem cell treatment
Adult stem cells used to cure diseases through transplants e.g bone marrow transplants to produce new blood cells in sickle cell anaemia.
Embryonic stem cells may be able to be used to be stimulated to differentiate into specialised cells
Risks of stem cell treatment
Transplanted cells can be rejected as body recognises them as foreign and triggers an immune response. Drug can be taken to suppress this but makes patient susceptible to disease
Tumor development - stem cells divide quickly so it can go out of control
Disease transmission if donor cells are infected
Ethical issues of harvesting human embryos - potential life
Nervous system
Receptor detects a stimulus and convers to a electrical impulse
Sent along sensory neurones to the Central Nervous System (brain and spinal chord) where a response is coordinated and impulses in CNS travel through the CNS along relay neurone
CNS sens information to an effector (muscle or gland) along motor neurone and effector responds accordingly
What is a neurone
A cell with a cell body that has long extensions that connect to other neurones
Dendrons and dendrites - carry impulses toward the cell body
Axons - carry impulses away from cell body to axon terminal to be passed to a dendrite in synapse
Neurones are very long to speed up impulse (synapses [connections] slow down impulses)
Sensory neurone
One long dendron carries nerve impulses from receptor cells
One short axon carries nerve impulses from cell body to CNS
Motor neurone
Many short dendrites carry nerve impulses from the CNS fo cell body
One long axon carries nerve impulse from cell body to effector cells
Covered by myelin sheath to insulate axon to speed up impulse and improve reaction time
Relay neurone
Many short dendrites carry nerve impulses from sensory neurones to cell body
One axon carries nerve impulses from cell body to motor neurones
