Please enable JavaScript.
Coggle requires JavaScript to display documents.
Biology - Topic 1 - Cell Biology (Binary Fission - (How to work it out -,…
Biology - Topic 1 - Cell Biology
Cells -
Plant and Animal Cells have similarities and differences
-
Plant -
2)
Permanent vacuole - contains cell sap, It supports the cell and strengthens it.
3)
Chloroplasts - where photosynthesis occurs they contain chlorophyll.
1)
Rigid cell wall - made of cellulose. It supports the cell and strengthens it.
4)
Mitochondria - these are where most of the reactions for aerobic respiration take place.
5)
Ribosomes - these are where proteins are made in the cell.
Animal -
3)
Cell membrane - holds the cell together and controls what goes in and out.
4)
Mitochondria - these are where most of the reactions for aerobic respiration take place.
2)
Cytoplasm - gel-like substance where most of the chemical reactions happen, contains enzymes which control it.
5)
Ribosomes - these are where proteins are made in the cell.
1)
Nucleus - Contains genetic material that controls the activities of the cell.
Bacterial Cells -
Bacterial cells don't have a nucleus - there is no membrane separating the genetic material from the other organelles - the DNA which floats freely.
They may also contain one or more small rings of DNA called plasmids.
Bacteria don't have chloroplasts or mitochondria, only cell wall, cell membrane and cytoplasm.
Organisms can be Prokaryotes or Eukaryotes -
2)
Eukaryotic
cells are complex and include all animal and plant cells -
Prokaryotic
cells are smaller and simpler
3)
Eukaryotes are organisms that are mad up of eukaryotic cells.
1)
All living things are made of cells.
4)
A prokaryote is a prokaryotic cell.
Chromosomes and Mitosis -
Chromosomes -
You get 23 chromosomes from each parent
Each chromosome carries a large number of genes and different genes control the development of different characteristics.
The cell cycle and Mitosis
3)
It duplicates its DNA and the DNA is copied and forms x-shaped chromosomes. Each arm is an exact duplicate.
4)
MITOSIS** The chromosomes line up at the centre of the cell and cell fibres pull them apart.
2)
Before it divides the cell has to grow and increase the amount of sub cellular structures.
5)
Membranes forma round each of the sets of chromosomes, these become the nuclei.
1)
In a cell that's not dividing, the DNA is all spread out in long strings.
6)
Cytoplasm and cell membrane divide, the cell has now produced two new daughter cells and they contain the exact DNA.
Time taken for cell cycle can vary depending on tissue type and age
Binary Fission -
3)
The cytoplasm begins to divide and new cell walls begin to form.
4)
The cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of the circular DNA, but can have a variable number of copies of plasmid(s).
2)
The cell gets bigger and the circular DNA strands move to the opposite ends.
How to work it out -
2)
Divide the total time that the bacteria are producing cells by he mean division time.
3)
Multiply 2 by itself for the number of divisions to fin the number of cells.
1)
Make sure both times are in the same units.
1)
The circular DNA and plasmid(s) replicate.
Exchange Surfaces
The bigger an object the smaller the surface area to volume ratio is.
Exchanging Substances -
Lungs -
2)
To do this lungs contain millions of little air sacs called alveoli.
3)
The alveoli to maximise the diffusion the have enormous surface areas, thin walls, a good blood supply and a moist lining.
1)
Job of the lungs is to transfer oxygen to the blood and remove carbon dioxide.
Villi -
2)
They increase the surface area so the food is digested more quickly into the blood,
3)
A single layer of surface cells, very good blood supply.
1)
The inside of the small intestine is covered in millions of villi.
Features that make a good exchange surface
1 - thin walls - less distance for substance to travel. 2 - large surface area - more surface for exchange to occur over. 3 - good blood supply - maintains the concentration gradient
4 - in the lungs - moist - to allow gases to dissolve
Microscopy and Magnification -
Magnification=image size divided by real size
The different kinds of microscopes.
Electron Microscopes - have a higher magnification then light microscopes and use a beam of electrons instead of light, they also have a higher resolution which gives a sharper image. They let us see smaller things in more detail e.g plasmids. Resolution is the ability to distinguish between 2 points
Light Microscopes - uses light and lenses to form an image of a specimen and magnify it they let us see nuclei.
I = image size A = actual size M = magnification
Stem Cells -
May be able to cure many diseases -
Adult stem cells transferred from the bone marrow of a healthy person can form many types of cells including blood cells.
Embryonic stem cells can be cloned and made to differentiate into many types of different cells -
Therapeutic cloning can have the same genetic information as the patient (adult body cell - nucleus removed - inserted into a denucleated egg cell and an embryo produced by giving the egg cell an electric shock to stimulate division. This means the embryonic stem cells will have the same genetic information as the patient so the body will not reject the stem cells and replace faulty cells. May be able to help in conditions like diabetes and paralysis
Some risks as the stem cells in the lab may become contaminated with a virus which could be passed on to the patient and make them sicker.
Can produce identical plants -
In plants, stem cells are found in the meristems (where growth occurs). Throughout the plants entire life, cells in the meristem tissues can differentiate into any type of plant cell. These stem cells can be used to produce clones of plants quickly and cheaply. They can be used to grow more plants of rare species to prevent extinction. Stem cells can also be used to grow crops of identical plants that have desired features for farmers, for example, disease resistance.
Against stem cell research -
Some people are against stem cell research because they feel that human embryos shouldn't be used for experiments since each one is a potential human life.
Others think that curing existing patients who are suffering is more important than the rights of embryos.
One fairly convincing argument in favour of this point of view is that the embryos used in the research are usually unwanted ones from fertility clinics which, if they weren't used for research, would probably just be destroyed. But of course, campaigners for the rights of embryos usually want this banned too.
These campaigners feel that scientists should concentrate more on finding and developing other sources of stem cells, so people could be helped without having to use embryos.
In some countries stem cell research is banned. It's allowed in the UK as long as it follows strict guidelines.
Can turn into any type of cell -
Differentiation is the process by which a cell changes to become specialised for its job. Undifferentiated cells, called stem cells, can divide to produce lots more undifferentiated cells. They can differentiated cells. They can differentiate into different types of cells depending on what instructions they are given. Stem cells are found in early human embryos. They're exciting to doctors and medical researchers because they have they potential to turn into any kind of cell at all.
Exchanging materials -
Active transport-
process by which dissolved molecules move across a cell membrane from a lower to a higher concentration. In active transport, particles move against the concentration gradient - and therefore require an input of energy from the cell. Such as the villi have a large surface area a single layer of surface cells and a good blood supply to assist absorption.
Osmosis-
Movement of water from a less concentrated solution to a more concentrated solution through a partially permeable membrane. In both solutions water is the solvent.
Water molecules move from a region of high water concentration to a region of low water concnetration
Isotonic -
Balanced concentration.
Hypertonic -
Higher concentration of the solute. Less water
Hypotonic -
Lower concentration of the solute. More water
Diffusion-
occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when the particles are free to move. Such as in the lungs where they have a enormous surface area, very thin walls, a good blood supply, a moist lining for dissolving gases.
Cell Differentiation and Specialisation -
Muscle cells are specialised for contraction -
Contain lots of mitochondria to generate the energy needed for contraction. Fibres in the muscle cells can shorten to cause contraction
Root hair cells are specialised for absorbing water and minerals -
The long "hairs" which are projections of the cell, gives the plant a big surface area for absorbing water and mineral ions.
Nerve Cells are specialised for rapid signalling -
These cells are long and have branched connections at their ends to connect to other nerve cells and form a network throughout the body. Long axon - projection from cell body to travel distances from extremities of body to the CNS. Also have a Myelin Sheath around the axon that increases the transmission of the electrical impulses
Phloem and Xylem cells are specialised for transporting substances -
Xylem cells are hollow in the centre - they are dead cells that form a network through out the plant. Phloem cells have very few subcellular structures, so that stuff can flow through them. - they have sieve plates at each end - glucose carried in the phloem - can move up and down the plant
Sperm Cells are specialised for Reproduction -
Long tail and a streamlined head to help it swim. There are lots of mitochondria in the cell to provide the energy. It also carries enzymes in its head to digest through the egg cell membrane.
