Cells- A-Level Biology

look in a textbook for pictures cause i don't have them

golgi apparatus

a system of folded membranes that produce vesicles to package and transport proteins (made by ER) throughout the cell

lysosomes

membrane bound vesicles containing digestive enzymes which destroys unwanted materials in the cell (lysozymes)

ribosomes

carries out protein synthesis (found in cytoplasm and on RER)

DNA usually exists as

chromatin

Nucleolus

dark areas inside the nucleus; rRNA synthesis

structure of the nucleus

largest organelle, contains DNA within a double membrane, has nuclear pores to allow passage of RNA molecules

function of nucleus

contains DNA and controls cell division and function

structure of mitochondrion

consists of a double membrane, inner membrane produces structures called cristae

function of mitochondrion

produces ATP (source of energy for cellular activities)

structure of rough endoplasmic reticulum (R.E.M.)

thin channels of folded (phospholipid) membranes covered in ribosomes

structure of smooth endoplasmic reticulum (SEM)

similar to R.E.M. but has no ribosomes on its membranes (smooth tubular appearance)

function of rough endoplasmic reticulum

synthesises and transports proteins around the cell

function of smooth endoplasmic reticulum

Synthesises lipids

centriole

aids in cell division

microfilaments

aid in the movement of cells

7 structures found in both animal and plant cells

nucleus, EM, ribosomes, golgi, lysosomes, cell membrane, mitochondrion

3 structures only found in plant cells

vacuole, chloroplasts and cell wall

2 structures only found in animal cells

centriole and microfilaments

structure inside a chloroplast

has a double membrane, contains many stacks (grana) of thylakoids containing chlorophyll, surrounded by enzymes (stroma)

thylakoid membrane

disc shaped structures containing chlorophyll

grana (granum)

stacks of thylakoids

stroma

fluid inside the chloroplast containing enzymes (help catalyse reactions to make glucose)

function of cell walls

gives plant cells strength and prevents bursting

structure of cell surface membranes

made of phospholipids (bilayer) and proteins (arranged like fluid mosaic model)

function of cell surface membranes

controls the passage of molecules in and out of the cell

resolution

the ability to separate out close together objects (and see them as separate objects)

magnification

how many times an object is enlarged

how do you use a transmission electron microscope (TEM?) step 1

samples are preserved and stained

how do you use a transmission electron microscope (TEM?) step 2

it's then cut into very thin sample (so electrons can pass through)

how do you use a transmission electron microscope (TEM?) step 3

it's placed inside a vacuum chamber and magnetic lenses focus a beam of electrons though the sample

What type of image is produced from a TEM?

the image produced is black and white

how do you use a scanning electron microscope?

beams of electrons are bounced off the surface of samples to form very clear 3D images

how do you use an optical microscope?

light is focused through a condenser and specimen into multiple lenses to give an image magnified several hundred times

magnification equation

image size/actual size

1mm (\=)

1000 micrometers

1 micrometer (\=)

1000 nanometers

1 mm (\= nanometers)

1 million manometers