B1: Cell-level Systems

cell types, DNA, respiration all that

Eukaryotic cells

-they contain a nucleus

-10-100 μm (micrometers)

-an example is plant and animal cells

Prokaryotic cells

-no nucleus

-1-10μm

-an example is bacteria cells

subcellular structures in an animal cell?

-nucleus

-cell membrane

-mitochondrion

-cytoplasm

subcellular structures in a plant cell?

-chloroplast

-vacuole

-cell wall

-cytoplasm

-nucleus

-mitochondrion

-cell membrane

bacteria:

-smallest living organism- it is a unicellular organism

-around 1μm in size

subcellular structures in prokaryotes?

-cytoplasm

-cell wall

-cell membrane

-genetic material (usually a circular strand of DNA

(some bacterial cells have extra, including flagella, pili, slime capsules and plasmids)

example of cell stains:

-methylene blue

-iodine

-crystal violet

electron microscope factors:

-expensive

-large + difficult to move

-complex to prepare

-black + white image

-specimens have to be dead

-resolution up to 0.1nm

light microscope factors:

-cheap

-small + portable

-easy to prepare stains

-natural colour of cells is seen unless a stain is used

-specimens can either be dead or alive

-resolution up to 0.2μm.

why are some cells stained for microscopy?

they are colourless

equation for magnification

magnification= image size/actual size

what is DNA made of?

phosphate, sugar and base

which bases bond together?

T and A

C and G

transcription

-DNA helix unzips

-RNA copies one of the strands using complementary pair bases (thymine- T- does not exist so A links to U instead pf T)

-mRNA detaches and leaves the nucleus once finished, the DNA helix zips back up

translation

-the mRNA is in the cytoplasm

-it attaches to a ribosome, the ribosome reads the nucleotides in triplets, called codons. Each codon codes for an amino acid.

-once completed, the amino acids join together in a chain, called a protein. The order of amino acids determines the type of protein

what are enzymes?

biological catalysts, made of proteins

lock and key hypothesis?

the idea that enzyme’s active site will only bond to the substrate with a complimentary shape to it

enzymes break down…

larger molecules into smaller ones

factors affecting enzymes:

-temperature

-pH

-ratio of enzyme to substrate (too little substrate for example)

How does temperature affect the rate of reaction with an enzyme?

higher temperature = faster rate of reaction, until it reaches its optimum pH; the enzyme denatures after 40 degrees

How does pH affect the rate of reaction with an enzyme?

every enzyme has an optimum pH. After it reaches this, it denatures

what is metabolic rate?

the speed in which chemicals transfer energy from food

what are lipids?

fats and oils you eat- they are a good source of energy

what enzyme breaks down starch?

amylase

what enzyme breaks down protein into amino acids?

protease

what enzyme breaks down lipids into fatty acids + glycerol?

lipase

aerobic respiration

glucose reacting with oxygen to create energy, as well as carbon dioxide and water

glucose + oxygen = carbon dioxide + water

what is produced during aerobic respiration?

ATP (adenosine triphosphate)

what is the energy produced during respiration used for?

-to make new cell material

-helping the organism move

-to stay warm

where does respiration occur?

the mitochondrion

is respiration exothermic or endothermic?

it is exothermic

what is anaerobic respiration?

during exercise, your body needs more oxygen than available, so the body converts chemical stores of glucose to lactic acid

why does the body usually respire aerobically?

-it produces more ATP, as it fully breaks glucose down

-the lactic acid produced can build up, causing cramps

what is fermentation?

anaerobic respiration in plant cells and microorganisms.

word equation for fermentation?

glucose ← ethanol + carbon dioxide

what is photosynthesis?

to make food, plants take in water from the roots and carbon dioxide from the air. They react together to create glucose, which the plant uses as food.

what is the byproduct of photosynthesis?

oxygen, which is sometimes used for respiration or released back into the environment

word equation for photosynthesis?

carbon dioxide + water → glucose + oxygen

symbol equation for photosynthesis?

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

where does photosynthesis occur?

the chloroplasts- it is where the carbon dioxide and water react to create glucose

is photosynthesis exothermic or endothermic?

it is endothermic

what is happened to the glucose produced in photosynthesis?

-some is used in respiration

-turned into starch, to be used as a store of energy and can be used at night for respiration

-turned into cellulose which is used to build cell walls

how does light intensity affect the rate of photosynthesis?

the higher the light intensity, the faster the rate of photosynthesis (until it reaches its maximum rate)

how does carbon dioxide affect the rate of photosynthesis?

the greater the carbon dioxide concentration, the faster the rate of reaction

how does temperature affect the rate of photosynthesis?

the higher the temperature, the faster the reaction (until the enzymes denature, causing reactions to stop)

what does chlorophyll do?

it absorbs light energy from the sun, and turns it into chemical energy

What is the difference between aerobic and anaerobic respiration?

Aerobic respiration happens in the presence of oxygen.

Fatty acids and glycerol are...

monomers of lipids

Where does aerobic respiration occur?

mitochondria

Where does anaerobic respiration occur?

cytoplasm

Why is respiration exothermic?

because it transfers heat energy to the environment