Biology theme 2

what are the 8 processes of life

1. homeostasis

2. metabolism

3. nutrition

4. movement

5. excretion

6. growth

7. response to stimuli

8. reproduction

what were the conditions on earth early on

lack of free oxygen

high concentration of CO2 and methane

high UV penetration

what were essential features for the first cell

1. catalysis: increase in rate of chemical reactions

2. self replication of molecules

3. self assembly

4. compartmentalization

miller and urey experiment

proved that organic compounds could be produced from inorganic ones in earth’s early conditions

water was heated and evaporated, this was mixed with gases like methane and hydrogen and then electrical impulses were sent though and then it was cooled back down, the liquid left in the end had amino acids and organic monomers

early formation of vesicles

fatty acids spontaneously aligned into a spherical bilayer, allowing internal environment to be kept separate from external environment

RNA as presumed first genetic material

RNA has catalytic activity, can self-replicate, could have acted as genetic material and enzyme

LUCA

Last universal common ancestor, evidence that supports LUCA is the universal genetic code kept similar across most forms of life, other life is likely to have existed but was out-competed by LUCA

Evidence of origin of LUCA in hydrothermal vents

• world’s oldest fossils found near hydrothermal vents

• genetic sequences are highly similar in organisms

• high temps provide energy

cell theory

all organisms are composed of cells, and are the basic unit of life, and originated from pre existing cells

magnification formula

image size/actual size

techniques of microscope

freeze fracture microscopy: freeze the sample, break into small pieces

cryogenic electron microscopy: freeze a sample in ice to prevent damage

immmunofleurescence

cell labeled with fluorescent stains, so cell structure light up

prokaryotic cells + components

all organisms without a nucleus and membrane-bound organelles

• ribosomes (70s)

• cytoplasm

• naked DNA

• pili

• flagellum

• cell wall

• cell membrane

eukaryotic cells + components

cells with nucleus and membrane-bound organelles

• plasma membrane

• Ribosomes (80s)

• mitochondria

• Endoplasmic reticulum : protein modification

• Golgi apparatus : protein packaging

• vesicles

• vacuoles

atypical cell structure

different number of nuclei not just one

1. red blood cells: don’t have a nucleus

2. muscle fibers: elongated cells with nuclei

3. fungal cells: no diving walls

4. phloem sieve tubes: elongated cells no nucleus

endosymbiosis

the theory how eukaryotic cells evolved

a large anaerobic organisms engulfed a smaller prokaryotic cell that could produce energy, they developed a symbiotic relationship, the smaller cell underwent changes that became the mitochondria and started to provide the larger cell with ATP

evidence: the presence of mitochondria and 70S ribosomes

cell differentiation

the developement of cellls, by different genes being turned on or off resulting in a certain cell

simple diffusion

passive movement of particles down concentration gradient without proteins, based on size and polarity

facilitated diffusion and channel

passive transport of mocules using proteins, such as channel proteins which open and close according to different triggers

active transport

the movement of particles up a concentration gradient using ATP and Protein pumps

glycoproteins and glycolipids

glycoproteins: carbohydrates + proteins

glycolipids: carbohydrates + lipids

• cell to cell adhesion, recognition and signalling

Endocytosis + example

the movemnt of molcules inot cell forming vesicles

eg. whit eblood cells, engulf bacteria then fuse with lysozomes wehre the bacteria is broekn down by enzymes

exocytosis + example

the removal of molecules from cell throuhg vesicles

eg. insulin is stored in vesicles in the pancreas, when high blood sugar levels are detected, insulin is realsed from pancreatic cells and enters the bloodstream

neurotransmitter ion gated channels

ion gated channels are triggered by neurotransmitters binding to receptors

neurotransmitters bind to Acetylcholine receptors opening channels, allowing ions like K and Na to pass through —> changing membrane potential—> sending impulse

sodium-potassium voltage-gated channels

channels open and close in response to voltage changes

with sodium-potassium pumps when there is a change in polarity channels open allowing diffusion of molecules in and out of the cell

structures common to viruses

DNA or RNA as geentic material

capsid made of protein

no cytosplaasm

few or no enzymes

Cholesterol as membrane regulator

works to regulate memrbane fluidity at different temeprature

• cold temperatures, more cholestrol, prevent tight orientation of phospholipids—> preventing stiffening

• warm temperatures, less cholestrol, creates tights orientation of phospholipids —>. maintains tight composition of phospholipids

bacteriophage lambda composition

• capsid head protects double-stranded DNA

• Tail fibres attach the virus to the host cell

• tail sheath that contracts to drive tail tube through host cells outer membrane

  • DNA injected through tail into host cell

Coronavirus composition

• spherical shape

• single stranded RNA

• envelope outside capsid

• projections of spike proteins (recognition molecules)

HIV composition

• spherical

• two identical strands of RNA

• envelope and capsid

• spikes are glycoproteins

• makes DNA copies of its RNA

• Transcriptase encoded in RNA

sodium cotransporters as an example of indirect active transport

Glucose must be absorbed into blood stream from the small intestine to enter the stream, but if their is high concentration of glucose in the cells of the small intestine then it can’t move down a concentration gradient, pulling glucose out into the small intestine.
But with active transport of sodium and potassium, a high concentration of Sodium is created within small intensive, meaning it has to go into the cells, but when doing so glucose is attached to it so it is able to more into the cells and into the capillaries

lyctic cycle

Phage injects DNA in Bacteria —> takes control of cells machinery —>more copies created of DNA and protein coat —> phage particles are put together —> bacteria undergoes lysis in which it bursts and many phages are released —> can infect new cells

lysogenic cycle

Bacteriophage attached to bacteria and injects DNA —> Virus DNA inserted into bacterial DNA —> Bacteria cell multiplies viral DNA in each daughter cell —> can then enter lyctic cycle and burst

theory for origin of viruses

because of obligate parasitism, it is believed that viruses evolved from cells, as they require host cell for functions of life

causes of rapid evolving viruses

rapidly evolving viruses cause issues with creating effective vacines and medication

rapid evolution is due to:

• high mutation rates

• short generation time

• large population size

mitochondria adaptations

• smaller intermembrane space: rapid proton accumulation

• matrix: contains fluids necessary for cellular respiration processes

• cristae: large surface area

chloroplasts adaptations

• many thylakoids: maximize absorbtion of sun light

• stroma: contains substances for photosynthesis

• thylakoid space: allows for proto gradient to accumulate

free ribosomes vs bound ribosomes

• free ribosomes: makes protiens for inside the cell use

• bound ribosomes: make proteins for outside cell use

Golgi apparatus

responsible for packaging proteins inside vesicles and transporting them