module 1

what are prokaryotic cells? (definition)

not containing a nucleus or any other membrane-bound organelles

features of prokaryotic cells:

• no nucleus
• most have cell wall
• unicellular
• bacteria and archaea
• cell membrane, vacuole, cytoplasm, ribosomes
• simple cell
• no membrane bound organelles
• plasma membrane
• DNA (circular strands)

what are eukaryotic cells? (definition)

containing membrane-bound organelles; nucleus

features of eukaryotic cells:

• nucleus
• some have cell wall
• multicellular and unicellular
• complex cell
• protists, plants, animal, fungi
• cytoplasm, nucleus, ribosomes, golgi bodies, vacuole, nucleolus, smooth and rough ER, mitochondria, chloroplast, lysosomes
• DNA (linear strands)

list types of prokaryotes:

bacteria + archaea

list types of eukaryotes:

protists, plants, animals + fungi

what is magnification?

the act of enlarging something to see detail

what is resolution?

the clarity + ability to see fine detail

what is a light microscope?

• light from mirror is reflected through specimen into lens • observe living cells
• cheaper, colour
• simple prep
• small and portable

what is an electron microscope?

• use beams of electron, focused by electric and magnetic fields, to form images
• higher magnification and resolution
• expensive
• b&w
• dead specimen
• expert prep

formula of magnification : ( eyepiece lens has a magnification of 10X and the objective lens has a magnification of 40X )

eyepiece lens x objective lens 10 x 40 = 400X

what is an organelle?

• an internal structure that has a specific job inside the cell
• most of the cells organelles are in cytoplasm
• some are membrane bound ( eukaryotic cells )

nucleus ( features, LM/EM, pro/eu + function )

• roughly spherical, ofter a dark centre usually the biggest • LM + EM • eukaryotic • control centre, sends messages to other organelles

cell membrane ( features, LM/EM, pro/eu + function )

• look for where the cytoplasm ends (can’t see it) • LM + EM • eukaryotic + prokaryotic ( aka plasma membrane ) • controls what enters / exit cell

cell wall ( features, LM/EM, pro/eu + function )

• thicker structure, often straight edge. • LM + EM
• prokaryotic + eukaryotic ( plants + fungi ) • protect cell, gives cell shape and supports it

cytoplasm ( features, LM/EM, pro/eu + function )

• everything that’s left, contained within cell membrane
• LM + EM
• prokaryotic (aka nucleoplasm) + eukaryotic
• contains water that dissolves substances for reaction • shape / supports cells

vacuole ( features, LM/EM, pro/eu + function )

• clear/white (empty space), large object in plant, animal = tiny
• LM + EM
• eukaryotic
• contains water, supports the cell

chloroplast ( features, LM/EM, pro/eu + function )

• black dots, darker lines. lines = length, larger, oval
• LM + EM
• eukaryotic
• photosynthesis

mitochondria ( features, LM/EM, pro/eu + function )

• lines go across smaller than
• EM
• eukaryotic
• cellular respiration (release energy)

endoplasmic reticulum ( features, LM/EM, pro/eu + function )

• tunnels, ‘room’ attached + usually next to nucleus
• EM
• eukaryotic
• provides channels for chemicals / messages to travel

ribosome ( features, LM/EM, pro/eu + function )

• dots located in cell or attached to ER
• EM
• prokaryotic + eukaryotic
• makes protein

golgi apparatus ( features, LM/EM, pro/eu + function )

• flat sacs, semicircular shape (membrane bound)
• EM
• eukaryotic
• contains digestive enzymes, destroy foreign protein

lysome ( features, LM/EM, pro/eu + function )

• circular
• EM
• eukaryotic
• digestion + waste removal

cilia ( features, LM/EM, pro/eu + function )

• rhythmic wave, hair like structure that’s extended outwards
• LM + EM
• eukaryotic + prokaryotic
• rhythmic, waving or beating motion; keep airways clear of mucus / dirt

flagella ( features, LM/EM, pro/eu + function )

• tail-like structure
• LM + EM
• prokaryotic eukaryotic
• enables motion

what is the fluid mosaic model?

a selectively permeable barrier rather than a closed wall or open gate

what molecules need the help of a protein channel?

large, polar molecules such as glucose

are phosphate heads hydrophilic or hydrophobic?

hydrophilic ♥︎

are lipid tails hydrophilic or hydrophobic?

hydrophobic X

formula of respiration:

glucose + oxygen ---> carbon dioxide + water + ATP
(cellular energy )

what are peripheral proteins?

• can be attached to ends of integral proteins, or not.
• helps with transport/communication

what does polar and non-polar mean?

polar : electrons not evenly distributed, one side more + or -- charged

non-polar : electrons evenly distributed so molecule evenly charged across surface

role of cholesterol in cell membrane:

holds phospholipids together so they don’t separate too far, let unwanted substances in, or compact too tightly restricting movement across membrane

role of glycoprotein:

• involved with cell recognition and immune response. • acts as receptor for hormones, help stabilise structure

role of glycolipid:

• acts as surface receptor and helps stabilise the membrane

what do both glycolipids and glycoprotein contain?

a glycocalyx (short carbohydrate chain)

what is the phospholipid bilayer?

main structure of membrane, allows small, lipid soluble molecules, uncharged to pass through simple diffusion

what is the protein receptor site?

allows other proteins to attach such as enzymes, antigens or chemicals like hormones

what is the protein channel?

pores filled with water which acts as channels for water soluble ions to pass through membrane by facilitated diffusion

what are the carrier protein?

can change shape to move certain substances which are too large to move by facilitated diffusion e.g. glucose - too big (active transport ATP energy)

are phosphate molecules polar or non-polar?

polar - it has a slight charge

are lipid tails polar or non-polar?

non-polar - it has no charge

role of integral proteins:

to transport large molecules across cell membrane

what is diffusion?

movement of particles from region of high concentration to region of low concentration until equilibrium is reached

what happens at equilibrium?

there is no net movement of particles in either direction

does diffusion require input of energy?

no

when does diffusion occur faster?

with higher temperatures + steeper concentration gradient

what molecules diffuse easily across cell membrane?

small, uncharged molecules ( O2 and CO2 )

what does facilitated diffusion allow?

larger molecules and small electrically charged ions to diffuse across cell membrane aided by carrier protein and protein channel

what molecules can go through each?

1. small uncharged molecules - O2 + CO2 ( cell membrane ) 2. large polar molecules - glucose ( protein channel ) 3. sugar + amino acids ( carrier proteins

what is osmosis?

movement of water molecules from a high concentration of water to a low concentration of water, through selectively permeable membrane

what is active transport?

movement of molecules from low concentration to high concentration through selectively permeable membrane

what is hypotonic?

solute concentration surrounding the cell is lower than inside the cell

what is isotonic?

solute concentration surrounding the cell is equal to inside the cell

what is hypertonic?

solute concentration surrounding the cell is higher than inside the cell

what is passive movement?

• movement down the concentration gradient
• no energy needed
• high concentration
• from higher concentration to lower concentration

what is endocytosis?

• large particle is moved into cell, • cell membrane can change shape to surround the particle and engulfs it • moves large molecules that can't cross cell membrane into a cell

what is exocytosis?

• substances are transported to external environment of cell. • a membrane bound vesicle moves to cell membrane, fuses then releases its contents to exterior of cell • vesicle membrane becomes part of cell membrane

what is phagocytosis?

when a solid particle is engulfed by cell membrane

what is pinocytosis?

• engulfing fluid substances by cell membrane • cell membrane engulfs a drop of extracellular fluid same ways as phagocytosis

formula for the magnification of cells:

I = A x M , A = I ÷ M , M = I ÷ A

formula for surface area (1cm cube)

1 x 1 x 6 = 6cm2

formula for volume (1cm cube)

1 x 1 x 1 = 1cm3

what is light energy?

• absorbed by the green pigment ( chlorophyll ) in plants, some protists and bacteria in a process called photosynthesis

• organisms that use light energy to make their own ‘food’ are called autotrophs

• autotrophic organisms can utilise light energy from the sun by absorbing it in chloroplast and converting it into glucose ( chemical energy ), in the process of photosynthesis

what is chemical energy?

• organic substances such as carbohydrates, lipids and proteins can be broken down to release energy by animals, some protists, fungi and some bacteria

• organisms that rely on taking in high-energy organic molecules as a source of energy are called heterotrophs

• heterotrophic organisms rely completely on chemical energy from consuming organisms containing glucose, in the process of cellular respiration

difference between autotrophs and heterotrophs?

Auto : ‘self feeder’
Make their own food
Carries out photosynthesis
Energy from sun converts to glucose e.g. plants, algae food

Heter : ‘different types of feeding
Cannot make their own food
Consumes other organisms.
Gets energy from other organisms
e.g. animals, single-celled organism

what do autotrophs and heterotrophs require?

• autotrophs require gases, simple nutrients and ions and water

• heterotrophs require gases, complex molecules and water

formula of photosynthesis:

carbon dioxide + water ---> glucose. + oxygen

where does photosynthesis occur?

in the chloroplast

what does photosynthesis do?

it uses light energy ( from sun, water, carbon dioxide ) to synthesis organic compounds ( glucose + oxygen )

does photosynthesis occur in autotrophs or heterotrophs?

autotrophs e.g. plants, algae + bacteria

where does cellular respiration occur?

different locations in the cytosol and mitochondria

what does cellular respiration do?

converts high-energy compounds ( glucose ) to ‘lower’ energy compounds

does cellular respiration occur in autotrophs or heterotrophs?

in both, it occurs in every living thing

role of enzymes in cells:

proteins that catalyse biochemical reactions, this allows them to be carried out at a sufficient rate to support living cells

what is metabolism?

sum of all chemical reactions occurring within a living organism

role of catalyst chemical substances:

• speed up chemical reactions • are unchanged at time of reaction and can be reused

what is activation energy?

minimum amount of energy required to a start reaction

how do enzymes speed up reactions?

• by lowering activation energy required for reaction • it combines reactants and holds them in a way that makes reactions more likely to occur

properties of enzymes:

• protein molecules are highly folded to create particular chemical shape

• surface of enzyme with specific shape is active site

• reactants ( substrates ) in chemical reactions temporarily bind and substrate-enzyme complex is formed and reaction proceeds

• products of reaction are released from active site of enzyme

• enzyme is unchanged and available for same process to occur

what are the models of enzymes?

lock and key model + induced fit

what is the lock and key model?

thought that the active site is rigid and small substrate molecule is reciprocally shaped and fits exactly into active site

what is the induced fit model?

suggests the binding of substrate to active site of enzyme induces the enzyme to alter its shape slightly to fit more tightly around substrate

what are the factors affecting enzyme activity?

temperature, pH levels and substrate concentration

effect of temperature on enzymes:

• function best at body temperature of organism they occur in

• rate of reaction increases until temperature is reached and at this point enzyme activity is at max level

• high temp can make protein structure bend and flex resulting in the active site changing shape

• heat causes enzyme to denature, change of structure in molecule is irreversible

• cold causes change of shape that is sometimes reversible

effect of pH levels on enzymes:

• each enzyme has its own pH range which it functions most efficiently

• extreme pH levels cause enzyme to denature

• most enzymes function near neutral

• protein digesting enzymes pepsin and renin function best in low pH ( high acidity )

effect of substrate concentration on enzymes:

• rate of enzyme-controlled reaction is affected by concentration of the substrate

• higher substrate concentration = greater rate of enzyme reaction, until all available enzymes are used to catalyse reaction (saturation point)

what is rennin?

aka chymosin a protein digesting enzyme that curdles milk by transforming caesogin into insoluble caesin

what is catalyse?

process which substance speeds up chemical reaction without being consumed or altered in process

what do amino acids form?

proteins

what is catabolic?

when one substrate is broken apart

what is anabolic?

when substrates join together

what is intracellular?

located or occurring within a cell

what is intercellular?

located or occurring between cells