Sb2 Flashcards
Mitosis
When a cell splits to form two daughter cells that are identical to the parent cell
Diploid
Two sets of chromosomes (46)
Haploid
One set (23)
What happens during interphase
Cell is copying itself and making copies of cell parts
The chromosomes that are copied attach togehter making an x shape
What order is mitosis
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
What happens in prophase
The nucleus starts to breakdown and spindle fibres appear
Nucleus has chromosomes in the middle with spindle fibres shown as a line in the membrane
What happens in metaphase
The chromosomes lineup on the spindle fibres across the middle of the cell
The chromosomes are in exes on spindle fibres in a straight line across the radius of the cell
What happens in anaphase
The chroma zones are separated and move to opposite ends of the cell on the spindle fibres
The exes have been separated on our parallel to each other across the radius
What happens in telephase
A membrane forms around each set of chromosomes to form nucleus
The cell is splitting into it looks like an eight with half the chroma zones in the top and a half the chromosomes in the bottom
What happens in cytokinesis
The cell surface membrane forms to separate the two cells so we are ended up with two daughter cells that are identical
Why do we need mitosis to happen
For growth and repair
What does asexual production produce
Offspring that are clones which means that their cells have the same chromosomes as the parent and they are genetically identical to the parent
What is an example of asexual reproduction
Strawberry plants reproduce asexually by using runner stems along the ground and this makes use of mitosis
Acids also reproduce asexually
what are the advantages of asexual reproduction
It is much faster than sexual reproduction
It doesn’t require finding a mate
It is efficient
What are the disadvantages of asexual reproduction
It doesn’t produce variation so if a disease or a changing environment happens they can wipe out a whole species because none of them have different characteristics that might enable them to survive
Cancer tumours
Or a result of excessive mitosis and are caused by changes in cells that turn them into cancer cells and they undergo uncontrollable mitosis. This rapid cell division produces lumps called tumours that can damage the body and results in cancer and sometimes death
Definition of growth
An increase in size as a result of an increase in number or size of cells
This can be recorded by taking measurements over time like length mass or weight
Why is growth not charted in the first two weeks of a babies life in a percentile chart
Because they often lose weight as they are just a feeding from the breast rather than from the placenta
What does it mean if the 25th percentile for an eight month old baby is 8 kg
This means that 25% of all eight month old babies have a mass below 8 kg
75% of all eight month old babies have a mass above 8 kg
Cell differentiation
Is when less specialised cells are adapted through the process of differentiation to become specialised for other functions.
Adaptations of a red blood cell
No nucleus so there’s more space for haemoglobin to be carried
Large surface area allowing oxygen to diffuse in and out more quickly
Adaptations of a fat cell
Cytoplasm of fat cells is filled with large fat droplets. The fact is stored until the body needs energy
Adaptations of a nerve cells
Nerve cells have a long fiver that carries electrical impulses around the body
Muscle cell adaptations
Contain special contractile proteins that can shorten the cell
What are meristems
A group of cells near the end of each shoot that allows plants to continue growing. 30 divide rapidly by mitosis. These cells that are produced can then increasing length and differentiate into specialised cells
Adaptations of a xylem cell
Thickened water with stand water pressure
Tiny pores in wall to allow water and mineral salts to enter and leave
No cytoplasm so the vessel is empty for a flow of water to pass through it
Loss of cell walls to form a tube
Stem cells in plants
They can produce any kind of specialised cells throughout the life of a plant and these are found in the meristems
Embryonic stem cells
Can produce any type of specialised cells
Adult stem cells
Can only produce the type of specialised cell that is around them
How are stem cells used to treat different diseases
They are stimulated to produce the specialised cell that are needed and then injected into the place required. Embryonic stem cells are the best to use for this because they can specialise into any cell, we use bone marrow stem cells in the cases of blood disease.
Problems with stem cells
Problems with stem cells include that if they continue to divide inside the body they can cause cancerous tumours
There are ethical issues with the way that embryonic stem cells are harvested
And stem cells from one person often killed by the immune system of another because it is rejected the stem cells
What does the cerebral cortex do
It is used for offenses language memory consciousness and behaviour. It is divided into two cerebral hemispheres that have different functions the right hemisphere communicates with the left side of the body and vice versa
Hippo Campus
Located underneath the cerebral hemispheres and is thought to be involved in memory and navigation
Cerebellum
The base of the brain is divided into 2 halves
Controls balance and posture. Coordinates the timing and fine control of muscle activity making sure movements are smooth musicians have developed a bigger cerebellum because they have fine hand movements when they play their instrument
Medulla oblongata
Connects to the spinal cord
Controls your heart rate and your breathing right
And is responsible for reflexes like vomiting sneezing and swallowing
