1. Cells Amanda Dunne Every living thing has cells-not all the same kind
Humans have Eukaryotic cells –3 main areas: nuclues, cytoplasm, membrane
with a nucleaus that contols & directs cell activities
Cytosol; fluid found in the gel like cytoplasm that fills most of the cell-this contains the oganelles
Plant cells thick fibrous walls-we have semi-permeable membranes
Amanda Dunne

2. Cells are the basic structural and functioning unit of the body.
The behaviour of the body is a combination of the activity of it’s cells.
The study of cells is
cytology, the study of tissue composed of cells is
histology.

4. Structure of an animal cell

5. Entrance into the cell Diffusion Osmosis Active transport
Diffusion- simple & facilitated (02.c02, N, H gases, fatty acids, steroids, fat soluble vits)
No energy req, passive form of transport, Simple:will pass if lipid soulble, uncharged or v small
Facilitated: allows non-polar (those that don’t bond with water) to pass thro via channel proteins in cell membrane (K, Cl, Na, Ca2 & glucose, galactose,fructose)
Osmosis- high-low movement of water (cells are 1% soulte & 99% sovlent) water is a polar molecule & can’t pass throu lipid bilayer- but is small enough to pass through (wihtout taking the substance dissolved in it) (hypertonic, isotonic, hypotonic)
Active transport-movement of substance e.g. amino acids. Ions, against the normal concentration gradient. Thrfr needing ATP to facilitate along with carrier/transport proteins ((Na, K, Ca, H I, Cl) also
Transport in vesicles bacteria, viruses, dead cells, other solutes, neurotransmitters, hormones & digestive enzymes

6. Nucleus Largest cell organelle (10%)and controls the cells activities.
Holds a complete set of genes
DNA(deoxyribonucleic acid) packaged in chromatin structures
Nucleolus stores RNA (ribonucleic acid) & produces ribosomes (information to regulate protein synthesis)
DNA carries all the genetic information for the organism.
During cell devision the chromatin contract to form chromosomes
Chromosomes contain a DNA molecule encoded with the generic information needed to direct the cell’s activities
The nucleus undergoes either MITOSIS or MEISOS in cell reproduction.
Surrounded by a nuclear membrane which is a selective barrier between the nucleoplasm and the cytoplasm. This membrane, called the nuclear envelope is also a phospholipid bilayer as are the membranes of all cell organelles.
Nuclear pores, circular arrangements of proteins surrounding a large central channel control the movement of substances in and out.
All cells have a nucleus except the red blood cells, which only have a nucleus while in their immature state.
Within the nucleus a nucleolus can be seen.

7. Cytoplasm
Gel like matrix (protoplasm that is inside the cell but outside the nucleus) wherein resides the organelles.
Cytoskeleton
Varies in composition and consistency from one cell to another typically being 75-90% water plus various dissolved solutes and suspended particles (ions, glucose, amino acids, fatty acids, proteins, lipids, ATP and waste products).
Many chemical reactions take place in the cytoplasm, most notably the break down of glucose in the first stage of cell respiration, the process that releases energy.
55% total cell volume
Cytoskeleton: network of fibrous proteins- (micro filaments, intermediate filaments & microtublues) maintain cell shape, enable it to move, anchor its organelles, & direct flow of cytomplasm

8. Organelles Centrosome Cilia Endoplasmic reticulum Golgi apparatus/body
Lysosome
Mitochondrion
Ribosomes
Vacuoles
Centrosome -
Cilia
Endoplasmic reticulum
Flagellum
Golgi apparatus
Lysosome
Mitochondrion
Ribosomes
Vacuoles
Research & share

9. What do cells do?? Respiration Growth Excretion Movement Irratibility
Reproduction

10. Protoplasm
Gel like matrix that fill the cell. Its mainly water but contains various compounds such as organic and inorganic salts, carbohydrates, fats, amino acids, proteins etc. It is made up of nucleoplasm inside the nucleus.

11. Chromosomes
Cell genes (hereditary units) made of DNA are found within the nucleus. Normally the cant be seen but can be visulised as beads on a string.
When the cell is not undergoing reproduction, these ‘strings’ are known as chromatin.
When the cell is replicating the chromatin winds up and shortens, and along with proteins called histones, become visible under the microscope as chromosomes. Chromosomes at this stage are composed of two chromotids, joined a the middle by a centromere.
All human cells except for gametes (sperm and ova) should containt 46 chromosomes in 23 pairs, one of each pair comes from each parent.
Chromosomes are vital in protein synthesis, cell reproduction (mitosis) and gamete formation (meiosis).
Make sure you are clear about the difference between chromosomes, chromatin and chromatids.

12. mitochondria The ‘power house’ of the cell.
Responsible for energy production in the form of ATP.
Cells with a larger energy requirement such as muscle cells have a large number of these.
Mitochondia are the site of cellular respiration to produce cellular energy (ATP)
This entails the breakdown of glucose to release energy.
The ATP then leaves the mitochondrion and migrates to wherever energy is needed in the cell.

13. Ribosomes
Mainly situated on the Endoplasmic Reticulum but also can be found elsewhere in the cytoplasm.

14. Endoplasmic Reticulum
A series of hollow flattened membrane like sacs or canals, which are continuous with the nuclear membrane.
It has a range of functions and enables circulation to occur in the cell as substances are transported through the middle.
There are two types, rough endoplasmic reticulum (RER), so called because its surface is dotted with ribosomes is where most protein and membrane molecule synthesis takes place (because of the ribosomes).
Smooth endoplasmic reticulum (SER) which lacks ribosomes is where fatty acids and steroids such as oestrogens and testosterone are synthesised.
Interestingly in the liver cells, enzymes of the smooth ER also help release glucose into the blood and inactivate or detoxify a variety of drugs and potentially harmful substances (alcohol, pesticides, carcinogens).
In the muscle cells, calcium ions needed for contraction are stored and released from a form of smooth ER called the sarcoplasmic reticulum.
The smooth ER builds up a tolerance in individuals who repeatedly take drugs, this increased drug tolerance is a result of the smooth ER detoxifying affects in the liver causing the individual to take higher and higher doses of said medication to get the desired effect.

15. Golgi Apparatus Aka Golgi body or Golgi complex.
Series of flattened sacks of membrane with vesicles at the edges. The vesicles pinch off and migrate into the cytoplasm.
They contain products from the Endoplasmic Reticulum which are passed onto the Golgi Apparatus to be further refined before being released from or used by the cell.
Cells that have a major secretary function such as pancreas cells contain the most well developed Golgi bodies

16. Lysosomes
Membranous sacs produced as vesicles from the Golgi apparatus.
Contain powerful digestive enzymes which aid in the disposal of intracellular bacteria, other foreign bodies, unwanted organelles and cell debris.

17. Vacuoles Membrane lined spaces within the cytoplasm.
Contain waste materials or secretions and are used for storage or digestion purpose until their contents can be removed from the cell.

18. Cell division
Cell division is essential for survival. When a cell divides, the nucleus divides first, followed by the cytoplasm.
The period between nuclear divisions is known as interphase. During this phase the choromsomes are in the form of a very long thin threads and regulate the activity of the cell.
Well before division occurs, each chromosome makes a replica of itself and is temporarily known as a chromatid.
When the nucleus divides the chromatids are distributed between the daughter cells.
Interphase is not a resting phase, it is a period of intense metabolic activity as the cell does most of its growing.
There are two types of nuclear division depending on whether the number of chromosomes in the daughter cells are the same as the parent cell or half

19. mitosis
In the human body, new cells (somatic or general body cells) are produced for the growth of new tissue and the repair of existing tissue by mitosis.
In this type of division two ‘daughter’ cells are formed, which are genetically identical to the ‘parent’ cell.
For this reason, mitosis is also known as a replicative division.
This type of division occurs for example in growth, hair follicles, skin cells, red bone marrow, nail beds and the lining of the gut.

20. Human body cells contain 46 chromosomes in 23 pairs, one member of each pair originating from each parent. This is called the diploid number, denoted 2n.
After a mitotic division, each new daughter cell also contains the diploid number (2n) chromosomes.
Each daughter cell is identical to the parent cell.

21. . Stage What happens.. Very early prophase
Chromatids becoming shortened and thickened.
Prophase
Nuclear membrane breaks down and nucleolus disappears. Chromosomes can now be seen to consist of two strands called chromatids, joined at the centromere. Centrioles replicate and move to opposite sides of the cell, forming the spindles across cell equator.
Metaphase
Chromosomes line up across the centre of the cell, attached to the spindle at their centromeres.
Anaphase
Spindle fibres shorten and chromatids separate moving to opposite sides of cell.
Telophase
Chromatids, unwind and become less visable. They mass together at each pole of cell. New nucleoli form and new nuclear membranes begin to develop.
The nuclear membranes are fully formed and the chomosomes are no longer visible. Nuclei take on a granular appearance of interphase. .

23. Meiosis
The production of sex cells or gametes (sperm and ova) for the purpose of sexual reproduction.
Gametes must only contain 23 chromosomes (one member of each of the pairs found in somatic cells). This ensures that when the sperm and ova fuse at fertilization the embryo has the correct number of chromosomes again.
If this did not happen the number of chromosomes would double with each new generation.
In humans, 23 is known as the haploid number or n.
In meiosis, four daughter cells are produced from the parent in two cycles of division.

24. Inheritance of gender
All normal diploid human body or somatic cell nucleii contain 46 chromosomes made up of 23 pairs. One of each pair is inherited from out father and one from our mother.
Of these 23 pairs, 22 are identical but the 23rd is made of one chromosome shaped like a Y and one like an X. These are sex chromosomes, the pair that decides gender, the body cells of a female contains XX and of a male XY.
As sperm and ova are formed by meiosis, each gamete only has one sex chromosome. All ova contain one X and roughly have the sperm contain one X and half one Y.
The gender of the offspring depends on which chromosome is inherited from the father.