3.6 prokaryotic cells and viruses

Differences between eukaryotic and prokaryotic cells

(2 points)

E= larger and have a nucleus bounded by Nuclear envelope

P= smaller and have no nucleus or nuclear envelope

All bacteria have..

(2 points)

A cell wall which is made up of murein

This is a polymer of polysaccharides and peptides

How do bacteria further protect themselves apart from the cell wall?

By secreting a capsule of mucilaginous slime around this wall

Inside the cell wall of a bacteria is..

(3 points)

The cell surface membrane

Inside is the cytoplasm that contains 70S ribosomes

These ribosomes are smaller than those in the cytoplasm of eukaryotic cells (80S) but still synthesise proteins

What is murein?

( 2 points)

A polymer of polysaccharides and peptides

Make up cell wall of all bacteria

How does bacteria store food?

As glycogen granules and oil droplets

What form is the gentic material in bacteria?

( 2 points)

Circular strand of DNA

Separate From this are plasmids (smaller circular pieces of DNA)

What can plasmids do?

Reproduce themselves independently

give the bacterium resistance to harmful chemicals eg antibiotics

Used as vectors ( carriers of genetic information) in genetic engineering.

What are vectors?

Carriers of genetic information

Compare a prokaryotic cell to a eukaryotic cell

( 8 points for each) BLURT

P = no true nucleus, only an area where dna is found

E = nucleus with nuclear envelope

P = DNA is not.associated with proteins

E = DNA is associated with proteins called histones

P = some dna in the form of circular DNA called plasmids

E= no plasmids and DNA is linear

P= no membrane bound organelles

E= membrane bound organelles, eg mitochondria

P = no chloroplasts, only bacterial chlorophyll

E = chokorplasts present in plants and algae

P = ribosomes are smaller (70S)

E = ribosomes are larger (80S)

P = cell wall made of murein (peptidoglycan)

E = cell wall made up of cellulose / chitin in fungi

P = outer mucilaginous layer called a capsule

E = no capsule

What does the cell wall do in a bacterial cell?

( 2 points)

Physical barrier that exclude certain substances

protects against mechanical damage and osmosis lysis

What does the capsule do in a bacterial cell?

Protects bacterium from other cells and helps groups of bacteria stick together for further protection

What does the cell surface membrane do in a bacterial cell?

Acts as a differentially permeable layer, which controls the exit and entry of chemicals

What does the circular DNA do in a bacterial cell?

Posess the genetic information for the replication of bacterial cells

What does the plasmids do in a bacterial cell?

( 2 points eg)

Posseses genes that help the survival of bacteria in adverse conditions

eg produces enzymes that break done antibiotics

What are viruses?

( 2 points)

Acellular, non living particles

They are smaller than bacteria

Some viruses like the human immunodeficency virus…

( 2 points)

Are further surrounded by a lipids envelope

The lipids envelope ( or capsid instead) have attachment proteins which are essential to allow the virus to identify/ attach to a host cell

What do viruses contain?

( 2 points)

Nucleic acids such as DNA or RNA as genetic material but can only multiply inside living host cells

nucleic acid is enclosed within a protein called the capsid