2.6 Prokaryotic and eukaryotic cells

When did prokaryotic cells first sppear?

3.5 billion years ago - when earth was a very hostile environment

What conditions do scientists believe prokaryotic cells adapted to live in?

extreme conditions of salinity, pH and temperature

What are these prokaryotic cells that have adapted to extreme environment called?

extremophiles

What environments are extremophiles found in today?

hydrothermal vents and salt lakes (similar to environments that made up early earth)

What domain are prokaryotic cells a part of?

archaea

What type of hospitable environments have extremophiles been found in recently?

soil and the human digestive system

What is Salinity?

is the dissolved salt content of a body of water

What does unicellular mean?

an organism that consists of a single cell (single-celled organism)

What organisms are always unicellular?

prokaryotic organisms

Subcellular structures of a prokaryotic cell (9)?

cell wall, chromosomal DNA, ribosomes, flagella, plasmids, cytoplasm, plasma/cell surface membrane, cytoplasm, pili

Prokaryotic cell diagram?

…

How much DNA do prokaryotic cells usually contain?

one molecule of DNA- a chromosome

What happens to this chromosome to make it more compact?

it is supercoiled

What are the genes on the chromosomes grouped into (in prokaryotic cells)?

operons

What are operons?

a cluster of genes controlled by a single promoter, allowing for coordinated expression

How does being grouped into operons effect how genes act when being switched on or off?

a number of genes are switched on or off at the same time

What is the relative size of ribosomes determined by?

by the rate at which they settle or form a sediment, in a solution

What is the cell wall made out of in prokaryotic cells?

peptidoglycan

What is peptidoglycan also known as?

Murein

What is peptidoglycan?

a complex polymer

What is the complex polymer peptidoglycan formed from?

amino acids and sugars

When did the first eukaryotic cell appear on earth?

1.5 billion years ago

Main difference between eukaryotic and prokaryotic cells?

eukaryotic cells are much more complex

Where is the DNA present in eukaryotic cells?

the nucleus

What is the DNA present as in eukaryotic cells?

supercoiled chromosomes

What does each chromosomes wrap round in eukaryotic cells?

histones

Histones?

proteins that provide structural support for a chromosomes

Why do chromosomes wrap around histones?

for efficient packaging

What is the complex of the chromosomes wrapped around histones called?

chromatin

What does chromatin coil and condense to form?

chromosomes

What kingdoms contain organisms composed of eukaryotic cells (4)?

plant, animal, fungi and protoctista

Differences between prokaryotic flagella and eukaryotic flagella?

flagella of prokaryotes is thinner and doesn't contain the 9+2 arrangement

Where does the energy come from that causes the flagella rotate in eukaryotic cells?

ATP

Where does the energy come from that causes the flagella rotate in prokaryotic cells?

the process of chemiosmosis

Prokaryotic cell: what is the flagellum attached to in a bacterium?

the membrane of the bacterium

Prokaryotic cell: What attaches the flagellum to the cell membrane?

a Basal body

Prokaryotic cell: what rotates the flagellum?

a molecular motor

Prokaryotic cell: What does the basal body do?

attaches the filament comprising the flagellum to the cell-surface membrane of a bacterium

Prokaryotic cell: What gives the filament a whip movement?

a motor molecule causes the hook/basal body to rotate

Prokaryotic cell: What does the filament (flagellum) having a whip movement do to the cell?

propels the cell

Size of ribosomes in prokaryotic cells?

70S (smaller)

Size of ribosomes in eukaryotic cells?

80S (larger)

What are both of these sizes of ribosomes necessary for?

protein synthesis

What are the larger (80S, eukaryotic) ribosomes involved in the formation of?

more complex proteins

Differences: Prokaryotic nucleus?

not present - DNA free in cytoplasm

Differences: Eukaryotic nucleus?

nucleus present - DNA inside nucleus

Differences: Prokaryotic DNA shape?

circular

Differences: Eukaryotic DNA shape?

distinctly linear (having distinct ends)

Differences: Prokaryotic cell size?

extremely small - less than 2μm in diameter

Differences: Eukaryotic cell size?

larger cells, 10-100 μm in diameter

Differences: is the cytoskeleton present in prokaryotic cells?

yes

Differences: is the cytoskeleton present in eukaryotic cells?

yes - but more complex

Differences: how do prokaryotic cells reproduce?

binary fission

What is binary fission?

the process of asexual reproduction and cell division in prokaryotic cells

Differences: how do eukaryotic cells reproduce?

asexual or sexual

Differences: prokaryotic cell type?

unicellular (single celled organism)

Differences: eukaryotic cell type?

unicellular and multicellular

What type of cells is the cell surface (plasma) membrane present in?

prokaryotic and eukaryotic cells

Differences: what is the cell wall made out of in prokaryotic cells?

peptidoglycan

Differences: what is the cell wall made out of in fungi (eukaryotic) cells?

Chitin

Differences: what is the cell wall made out of in plants (eukaryotic) cells?

Cellulose

Differences: what type of cell is the cell wall not present in (eukaryotic)?

Animal cells

Diagram of a prokaryotic flagellum?

…

Differences: the type of organelles in prokaryotic cells?

non-membrane bound

Differences: the type of organelles in eukaryotic cells?

both membrane-bound and non membrane-bound organelles.

Differences: the number of organelles in prokaryotic cells?

few organelles

Differences: the number of organelles in eukaryotic cells?

many organelles

Differences: how is the DNA organised in prokaryotic cells?

Differences: how is the DNA organised in eukaryotic cells?

Linear chromosomes in the nucleus, organized around histone proteins.

Differences: What is the extra chromosomal DNA in prokaryotic cells?

circular DNA called Plasmids

Differences: Where is extra chromosomal DNA present in eukaryotic cells?

only present in some organelles such as chloroplasts and mitochondria