IB Biology Topic 1

What are the 3 main points of the cell theory?

Cells are the smallest unit of life
All living organisms are made of cells
Cells can only come from pre existing cells

How does differentiation occur?

It involves the expression of some genes but not others in a cells genome.

What is MRS H GREN

Metabolism
Respiration
Sensitivity

Homeostasis

Growth
Reproduction
Excretion
Nutrition

How is hyphae an exception to the cell theory

They are so big they have multiple nuclei and are sometimes just one large cell

How are red blood cells an exception to cell theory?

They do not have a nucleus

How are skeletal muscle cells an exception to cell theory?

They have more than 1 nucleus.

What is the function of pilli?

helps prokaryotes stick to surfaces
transfer of genetic material between cells

What is the function of flagella

movement

What size are the ribosomes in prokaryotic cells?

70s

What is the function of a lysosome

break down cellular waste and debris

What is the function of Golgi apparatus?

sorts and modifies proteins that have arrived from the rough ER

What is the function of the smooth ER

lipid synthesis

What is the function of the rough ER

protein synthesis

What do plant cells have that animal cells don't?

chloroplast, cell wall, large vacuole
However they have no lysosome

How are phospholipids arranged in the cell membrane?

In a bilayer with the phosphates heads pointing towards the water inside/outside the cell and the fatty acid tails pointing into the center of the membrane.

Why are phospholipids arranged in a bilayer?

Because it consists of two hydrophobic phosphate heads and tails, the heads face each other, avoiding the cytoplasm, where the hydrophilic tails do face the liquid.

What are some properties of the phospholipid bilayer?

Restricts the passage of many substances including water and ions
Can spontaneously break and reform
Embedded with proteins

What is the spontaneous breaking and reforming of membranes called?

Endocytosis
Exocytosis

What are integral membrane proteins?

proteins that pass all the way through the membrane

What are peripheral membrane proteins?

proteins that bind to the membrane without passing through it

What is cholesterol used for in the cell membrane?

Structure and fluidity

What is an aquaporin?

water channel protein in a cell

What is the fluid mosaic model?

describes the arrangement of the molecules that make up a cell membrane
By Singer and Nicholson

What is the Davison-Danielli model?

Describes the membrane as a lipo-protein sandwich

How is the Danielli and Davson model falsified?

Membrane proteins are insoluble in water
Proteins are mobile

What is abiogenesis?

the original evolution of life or living organisms from inorganic or inanimate substances.

What are the 4 stages of abiogenesis?

Simple organic molecules were made by non living synthesis
These were assembled into more complex polymers
Certain polymers gained the ability to self replicate (inheritance)
Molecules become packed into membranes with an internal chemistry different to their surroundings.

Which experiment demonstrates the abiogenesis theory?

Miller-Urey experiment.

What is biogenesis?

the hypothesis that living organisms arise from preexisting life

What was the conclusion from Pasteurs experiment?

Cells can only arise from pre existing cells

What is the endosymbiotic theory?

explains how eukaryotic cells may have evolved from prokaryotic cells

What is some evidence for the endosymbiosis theory?

Mitochondria and chloroplasts have double membranes and are around the same size as prokaryotes

How do you convert from millimeters to micrometers?

X1000

What is the ideal surface area : volume ratio of a cell

lower ratio increases metabolic rates and exchange of materials

How does a light and electron microscope differ

an electron microscope has a higher resolution

How do bacterial cells reproduce

via binary fission

How does the organisation of eukaryotic and prokaryotic cells differ

Eukaryotic cells have membranes for compartmentalisation