BIOL 1102 - Lec 5 Domains of Life

about 3.5 billion years ago

origin of life on earth

Cyanobacteria

living organism that resembles the earliest fossils.

basic properties of life

• capacity for metabolism

• controlled responses to the environment

• growth

• self-reproduction

Metabolism

controlled chemical reactions that acquire and use energy

structural features all cells share

• plasma membrane

• DNA, RNA. and Ribosomes

• Cytoplasm

phospholipid compounds

Cell membrane is made from…

hydrophilic head and hydrophobic tail

Phospholipids have…

hydrophobic heads, hydrophilic tails

Cell membrane is a phospholipid bilayer with ______ outside and ______ inside.

DNA

the instructions for making protiens

RNA and ribosomes

read DNA code and make proteins

Cytoplasm

the water-based fluid inside the cell

Colonial

cell live together, but can live apart

Tissue

groups of cells with similar structure and function

Multicellular

cells cannot live alone

organ

group of tissues working together to perform a common function

Archaea, Bacteria, Eukarya

What are the three domains of life (types of cells)

Archaea and Bacteria

What domains are Prokayotes?

Features of prokaryotes

smallest cells. All are single celled organisms can live colonially.

• no nucleus around DNA

• plasmids

• DNA is circular not linear

• have cell wall and cell membrane

Plasmid

small loops of DNA shared among bacteria

Archaea

• no known diseases

• live in diverse, often extreme environments

• Methanogens in digestive tract create methane gas.

Bacteria

• Diverse and common

• gram positive and gram negative

Gram positive

antibiotics work well

Gram negative

antibiotics don’t work well

Eukayotes

formed from an endosymbiosis (one cell living inside another cell)

Step 1 (all Eukaryotic cells)

about 1.5 billion years ago, a bacterial cells lives inside. Archaean cell and evolved into the chloroplast. At the same time nucleus forms around the DNA.

Nucleus

double phospholipid bilayer that protects the DNA from the mitochondria

Step 2 (some protists/all plants)

a second bacterial cell moved inside a “step 1 cell” and evolved into the chloroplast.

Evidence that Mitochondria and chloroplasts were once free-living bacteria

• their own DNA, RNA and ribosomes

• the same genetic code as bacteria

• circular DNA like bacteria

Eukaryotic cells

more “complex and larger than prokaryotes

• single-celled or multicellular

• DNA in Nucleus (with membrane)

• DNA is linear (not circular)

• Endomembrane system, organelles and cytoskeleton

Endomembrane system

flattened sacs inside the cytoplasm

Endoplasmic Reticulum

provides surface area to make proteins and lipids

Rough ER

makes proteins

Smooth ER

makes lipids/fats

Golgi bodies

Transport proteins and fats around and out of the cell

Vesicles

Sacs that bud off ER, Golgi bodies, or cell mebrane

Lyososomes

digest things inside the cell

Peroxisomes

detoxify alcohol in liver cells

Vacuoles

fluid filled sacs that store food or water in plant cells or fats in animal cells

Cytoskeleton

protein filaments that give Eukaryotic cells shape, internal structure, help move the cell, and move things around inside the cell.

Microtubules

Move chromosomes during cell division

Kinesins

move chloroplasts in plant leaves as angle of sun changes.

flagella

usually one or a few long tails for movement

Cilia

usually many tiny ones all over cell for movement. (ex: sperm cells)