Biology - Module 2

What is the cell membrane’s role?

Controlling what comes in and out of the cell

What is the role of and details of the nucleus?

• Stores chromosomes and hence controls cell activities

• Has pores

• Contains nucleoplasm - a liquid which contains chromosomes and nucleoli. Substances dissolved in it too

What is the nucleolus made of and what does it produce?

• Made of RNA

• Ribosome production

What does the mitochondria do?

Releases cell energy as ATP

What do ribosomes do and what are they made of?

• Build proteins from anino acids in cytoplasm

• Free-floating or attached to rough endoplasmic reticulum

• Made of RNA

What is the endoplasmic reticulum, the two types, and how do you differentiate between them?

• It builds lipids and carbohydrates

• Rough or smooth

• Can tell the difference because ribosomes attach to the rough but not the smooth and rough stores proteins

What do the Golgi body, lysosomes and centrioles do?

• Golgi body: Packages proteins into vesicles to go to destination

• Lysosomes: Filled with digestive enzymes to digest food absorbed by cell

• Centrioles: Bundled tubes that organise cell division

What do plants contain that is unique to them and not in human cells?

• A cell wall made of celllulose which protects and prevents rupture

• A permanent vacuole filled with water, keeping the cell pressurised and storing starch

• Chloroplasts have chlorophyll, these convert light into chemical energy and therefore make photosynthesis possible

What do bacterial cells contain?

• Mesosomes (similar to mitochondria)

• Flagellum (helping them swim)

• Cell wall (for protection)

• Cell membrane (for filtering)

• Ribosomes

• Capsule (slime layer outside)

• Nucleoid (most DNA is stored here)

• Plasmid (some DNA is stored here)

What are microtubules and flagella/cilia?

Microtubules - 25nm cylinders of tubulin

Flagella/cilia - Hair like, out of surface of cell - forms a cylinder of microtubules. Flagella (undulipodia) are the longer of the two

What is the cytoskeleton?

• Made of microtubules

• Throughout the cytoplasm

• Provides shape to cell, moves organism around inside

What roles does the cytoskeleton have?

• Supports and shapes the cell

• Helps move cilia/flagella

• Allows shape change for functions

• Holds organelles in place

• Moves chromosomes

What are the steps of protein synthesis?

• Gene with coded instructions (housed on chromatin, wrapped up DNA) is transcribed into mRNA

• Copies of the gene are made, passing out of pores to ribosomes

• Instructions translated, molecules assembled at the ribosomes

• Protein molecules pass into the cisternae (membrane of the endoplasmic reticulum) along hollow sacs

• Vesicles with protein pass to Golgi apparatus via microtubules and motor proteins

• Fusion with Golgi apparatus

• Vesicles pinched off Golgi apparatus, passes to plasma membrane

• Vesicles and membrane fuse, protein released to outside cell

What is the difference between resolution and magnification?

Resolution: How well two objects can be distinguished under a microscope

Magnification: How detailed the image the microscope projects can be

What are the advantages and disadvantages of light microscopes?

Advantages: Relatively cheap, easy to use, portable, sufficient for whole specimens

Disadvantages: Limited resolution, use of visible light, close structures appear as one, ribosomes cannot be seen

What is the process of laser scanning?

• Laser light point by point

• Provides a high resolution/contrast

• Can see different layers

How do the two types of electron scanning work?

Transmission electron: Dehydrated or stained sample, electrons pass through, 2D black and white, up to 2,000,000x magnification

Scanning electron: Electrons trigger other electrons to bounce off, 3D image ranging from 15x to 200,000x, black and white

What are the disadvantages of electron microscopes?

Large, expensive, requires training

What is the formula for magnification?

Magnification = Image size/Actual size