Section 1: Cell Biology

What is the order of units, from largest to smallest?

Centimetres, millimetres, micrometres, nanometres

If numbers differ by 1 order of magnitude, they differ by a factor of?

Factor of 10.

If numbers differ by 2 orders of magnitude, they differ by a factor of?

Factor of 100.

Name all organelles in an animal cell.

Cell membrane, cytoplasm, nucleus, mitochondria and ribosomes

Name all organelles in a plant cell.

Cell membrane, cell wall, cytoplasm, chloroplasts, vacuole, mitochondria, and ribosomes

What is the function of the cell membrane?

It controls the movement of substances into and out of the cell.

What is the function of the cytoplasm?

Place where chemical reactions occur.

What is the function of the nucleus?

Controls the cell. Contains DNA in chromosomes - the instructions to make proteins.

What is the function of the mitochondria?

Where aerobic respiration takes place. Releases energy from glucose.

What is the word equation for aerobic respiration?

Glucose + oxygen —> carbon dioxide + water (+ energy)

What is the function of the ribosomes?

Site of protein synthesis (protein creation)

What is the function of the cell wall?

Keeps cell in shape (keeps structure together)

What is the function of the chloroplast?

Contains a pigment called chlorophyll where photosynthesis takes place

What is the word equation for photosynthesis?

Carbon dioxide + water —> glucose + oxygen

What is the function of the vacuole?

Contains a fluid called cell sap (contains water, sugar, and mineral ions). Helps with support

What is the piece of a microscope called that you can switch the power of? What powers does this piece have?

The objective lens.  Powers are x4, x10 and x40 magnification

Define magnification

The number of times larger an image is, compared to the actual size of the object.

What is the equation for calculating magnification?

Magnification (M) = size of image (I) / actual size of specimen (A) M = I/A

Name all organelles of a prokaryote.

Cell wall, cell membrane, slime capsule, cytoplasm, circular DNA, plasmids and the flagella

How is the genetic material structured in a prokaryote?

It is NOT in a distinct nucleus - it forms a single DNA loop

What are plasmids?

One or more extra small rings of DNA (separate from the circular DNA) in a prokaryote

What is a prokaryote’s cell wall made of?

Protein

What is a flagellum used for?

Movement

How does a light microscope produce an image?

It uses a series of lenses to produce a magnified image of the specimen

Who discovered cells and when?

Robert Hooke in 1665.

Who made higher quality lenses for light microscopes? What was the improved magnification?

Anton van Leeuwenhoek improved the magnification to x270.

What is the current maximum magnification of light microscopes?

x2000

Define resolving power

Ability to see two points as two points, rather than merged into one

If the resolving power NUMBER is small, is the resolution high or low?

HIGH

What is the resolving power of a light microscope?

200nm

How do electron microscopes produce an image?

They use beams of electrons instead of light rays - this means a vacuum is needed.

What is used instead of lenses in electron microscopes?

Electromagnets

What is the maximum magnification and resolving power of an electron microscope?

x2,000,000 magnification and resolving power of 0.2nm (or 200 picometres)

Is the image from an electron microscope colourful or black and white?

Black and white

Will the biological material being viewed from an electron microscope be living or dead, and why?

Dead, because electron microscopes require vacuums (no air) to work, so the organism will not be able to respire, meaning it will die.

Define and give an example of a unicellular organism

An organism made of one singular cell, e.g. Euglena

Are most organisms multicellular or unicellular?

Multicellular

What is a cool thing that multicellular organisms can do?

They can differentiate to perform different functions.

Define differentiation

To literally become a different thing

How do cells develop to carry out a specific function?

They develop specific shapes and particular sub-cellular structures.

What is the difference between differentiation in animal cells and plant cells? HINT: to do with time.

Most animal cells differentiate at an early stage, whilst plant cells keep the ability to differentiate throughout life.

What four main features does a sperm cell have?

An acrosome, a nucleus, mitochondria and a flagellum.

What is a sperm cell’s function?

To fertilise the female egg cell to form a baby.

What is the function of an acrosome?

It contains enzymes that help break down the barrier of the female egg cell to fertilise it.

What is the function of an nucleus in a sperm cell?

It controls the cell, and contains the male DNA that will fertilise the egg cell

What is the function of mitochondria in a sperm cell?

Many mitochondria are needed to perform aerobic respiration, releasing lots of energy. Lots of energy is needed for movement, because the sperm cell needs to travel a long distance to fertilise the egg cell.

What is the function of a flagellum in a sperm cell?

Used for movement towards the female egg cell.

What seven structures does a nerve cell have?

Dendrites, a nucleus, a cell body, nodes of ranvier, an axon, schwann cells, and axon terminals

What is the function of a dendrite?

It is used to send and/or receive electrical signals.

What is the function of the axon?

It is long, so information can pass through it long distance.

What is the function of schwann cells?

They are fatty (like rubber). They are natural insulators so electricity doesn’t affect other parts of the body.

Name the three types of muscle cells

Skeletal muscle cells, cardiac muscle cells, and smooth muscle cells.

What are the four features of skeletal muscle cells?

Striped, many nuclei, contain protein fibres that allow the cells to slide over each other, and many mitochondria.

What are the four features of cardiac muscle cells?

Striped, branched cells, one nucleus, many mitochondria

What are the three features of smooth muscle cells?

Spindle-shaped cells, one nucleus, and many mitochondria

Where are skeletal cells located and what is their function?

They are located around bones and joints and allow movement.

Where are cardiac cells located and what is their function?

Around the heart - help pump blood

Where are smooth cells located and what is their function?

For anything that needs to contract, for example the digestive system. They move food along the gut and change the size of blood vessels.

What are phloem and xylem cells?

Specialised cells for transport in plants.

What do xylem and phloem cells form when joined together?

Xylem cells form a xylem tube. Phloem cells form a phloem tube.

What do xylem and phloem tubes transport?

Xylem transports water and mineral ions. Phloem transports sugars.

What sugar does phloem transport?

Sucrose

Xylem vessels are…

hollow and dead

Phloem has little… to allow substances to flow through them

cytoplasm