Cell Structure

What is the function of coarse adjustment?

Rough focusing

What is the function of fine adjustment?

Precise focusing

What is the function of objective lens?

Magnifies the image

What is the function of nose piece?

Allows to move different objective lens into place

What is the function of the eyepiece?

magnifies the image

Clip

holds the slide in place

Stage

holds the slide

Condenser

focuses light on to the subject

Diaphragm

controls the amount of light entering the slide

Steps to use microscope

Place slide on stage & clip in place

Switch on light source

Use coarse focus knob to bring low power objective lens into focus

Now place high power objective lens into place & use fine focus knob to focus it correctly

What is cell ultrastructure

Using electron microscope to look at cell in greater detail compared to compound microscope

Structure of a cell membrane

Composed of phospholipids and proteins

Functions of a cell membrane

Selectively permeable

Selectively permeable

controls what substances enters and leaves the cell

Advantage of selectively permeable membrane

Allows useful substances to enter cell

Functions of Mitochondria

Supplies energy to cell

Site for respiration

Double membrane that is selectively permeable

Apart from nucleus where is DNA found?

Chloroplast & Mitochondria

Inactive Mitochondria

This mitochondria has very few infoldings and are inactive (low amount of energy released)

Active Mitochondria

The more infoldings that are present the more energy being produced

Exercise causes the number of infoldings to increase.

What is the location of plant mitochondria?

Meristem as they require more energy

What is the location of human mitochondria

Muscle and liver as they require more energy

Functions of nucleus

Control centre of cell

Nucleus has a double membrane which has many nuclear pores making it selectively permeable

contains DNA

Function of nuclear pores

Allow certain molecules to enter and exit the nucleus

e.g. allows mRNA to pass in and out of the nucleus.

Function of nucleolus

Ribosomes are made in the nucleolus

Cytoplasm

All living material inside the cell but outside the nucleus

Cytosol

Liquid part of cytoplasm

Vacuole

Contains cell sap (made of sugars and salts) which is a fluid

Chloroplast

Where photosynthesis takes place

Contains chlorophyll

Chloroplast is surrounded by a double membrane which is selectively permeable

Ribosomes

RNA and protein

Functions of ribosomes

Protein synthesis

to make proteins (many amino acids joining together) – protein synthesis is an anabolic reaction in a cell

What are cell walls made up of?

Cellulose

Function of cell wall

Support and strengthen the cell

Selectively permeable

Prokaryotic cell

These cells don’t have a nucleus or no membrane enclosed organelles

e.g. bacteria

Eukaryotic cell

These cells have a nucleus and membrane enclosed organelles

e.g. animals/fungi/plants

Onion cell experiment

Use forceps to pull a strip of thin, transparent epidermis from an inner leaf.

Place a small piece of the strip on the slide

Add iodine using a dropper

Add a few drops of water

Add a coverslip at an angle using forceps

Cheek cell experiment

Rinse your mouth

Scrape inside of your mouth with cotton bud

Spread the cells thinly on a glass slide

Add a few drops of methylene blue using dropper (stains the cell and nucleus a deep blue)

Add a few drops of water

Add a coverslip at an angle using forceps