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What are the two types of cells called?

Eukaryotic and Prokaryotic


Describe a Eukaryota cell

Complex cells e.g. animals and plants


Describe prokaryotic cells

Smaller and simpler e.g. bacteria


What is the nucleus

Surrounded by a double membrane called the envelope, which contains pores enabling molecules to enter and leave the nucleus. The nucleus also contains chromatin, and a nucleolus, which is the site of ribosome production.


What is the lysosome

Contains digestive enzymes used to digest invading cells or break down worn out cells.


What is the ribosomes

Composed of two subunits. The site of protein synthesis.


What is the rough endoplasmic reticulum

A series of flattened sacs enclosed by a membrane with ribosomes on the surface. The RER folds and processes proteins made on the ribosomes.


What is the smooth endoplasmic reticulum

A system of membrane-bound sacs. The sER produces and processes lipids.


What is the golgi apparatus

A series of fluid-filled, flattened and curved sacs with vesicles surrounding the edges which processes and packages proteins and lipids. It also produces lysosomes.


What is the mitochondria

Usually oval shaped and bound by a double membrane called the
envelope. The inner membrane is folded to form projections called cristae, with
matrix on the inside containing the enzymes needed for cellular respiration.


What is the centriole

Hollow cylinders containing a ring of microtubules arranged at right
angles to each other. Centrioles are involved in cell division.


Explain the protein production and transport in a cell

1. Proteins made at ribosomes.
2. Ribosomes on rER make proteins which are excreted or attached to cell membrane. Free floating ribosomes in cytoplasm make proteins in cytoplasm.
3. New proteins at rER are folded and processed.
4. Proteins transported from rER to golgi apparatus in vesicles.
5. Further processing at golgi apparatus.
6. Proteins enter more vesicles to be transported around cell to be secreted.


What is the cell wall

The cell’s rigid outer covering made of peptidoglycan. Provides the cell with strength and support.


What is the slime capsule

Protective slimy layer which helps the cell to retain moisture and adhere to surfaces.


What is the plasmid

circular piece of DNA.


What is the flagellum

A tail-like structure which rotates to move the cell.


What is the pilli

hair-like structures which attach to other bacterial cells.


What is the mesosomes

Infoldings of the inner membrane which contain enzymes required for respiration.


What is the formula for calculating the magnification of an image?

M = size of image
size of real object


How do you convert micrometers to millimeters?

Divide by 1000


Describe the light microscope

.Use light to form an image
.Maximum resolution of 0.2 micrometers
.Maximum magnification of x1500


Describe the electron microscope

.Use electrons to form an image
.High resolution of 0.0002 micrometers
.Maximum magnification of x 1500000


What are the two types of electron microscopes?

Transmission-TEM and scanning-SEM


Describe the transmission electron microscope

Use electromagnets to focus on beam of electrons which is transmitted through the specimen
Denser parts of the specimen absorb more electrons and look darker
High resolution images so internal structures of organelles are shown
Only used on thin specimens


Describe the scanning electron microscope

Scan beam of electrons across specimen
electrons gather at cathode ray tube to form image
3D images
used on thick specimens
lower resolution images


Describe multicellular organisms

Made up of lots of different cell types which are organised to work together.


Describe the structure of the ovum

.Zona pellucida- protective coating which prevents polyspermy
.Haploid nucleus- so full set of chromosomes is recovered
.Cortical granules- release substances to harden zona pellucida
.Follicle cells- digestive enzymes to break zona pellucida


Describe the structure of the sperm

.Mitochondria- provides energy for rotation of flagellum
.Acrosome- contains digestive enzymes to break zona pellucida
.Flagellum- rotates to move cell


What is the process of fertilisation

1) The sperm head meets the protective jelly layer around the egg cell called the zona pellucida and the acrosome reaction occurs – enzymes digest the zona pellucida.
2) The sperm head fuses with the cell membrane of the egg cell thus allowing the sperm nucleus to enter the egg cell.
3) The cortical reaction occurs which causes the zona pellucida to harden and prevents polyspermy.
4) The nuclei fuse and a full set of chromosomes is restored, thus forming a diploid zygote.


What is meiosis?

A type of cell division that happens in the reproductive organs to produce gametes.


How does meiosis happen

1. DNA replicates so there are two identical copies of each chromosome called chromatids
2. DNA condenses