b1- cell level systems (copy)

whats a eukaryote

cells which have a nucleus (e.g. all animals and plants)

whats a prokaryote

cells which dont have a nucleus (e.g. bacteria)

state the 5 parts of an animal cell

1. nucleus

2. cytoplasm

3. mitochondria

4. ribosomes

5. cell membrane

what are the 3 organelles only found in plant cells

1. cell wall

2. permanent vacuole

3. chloroplasts

what is the nucleus

contains dna in the form of chromosomes that controls the cells activities

whats the cytoplasm

gel- like substance where most of the chemical reactions take place

whats the mitochondria

carry out aerobic respiration so provide energy (in form of ATP) for cells to use in chemical reactions

what are ribosomes

where proteins are made in the cell (protein synthesis)

whats the cell membrane

• protective barrier around outside of cell

• controls which substances pass in and out of the cell

whats the function of the cell wall and whats it made of

• it provides strength and support for the plant cell

• is made of cellulose

whats the permanent vacuole and what does it contain

• it supports the cell to help keep it turgid

• contains cell sap ( solution of sugar and salts)

what are chloroplasts

• where photosynthesis takes place so they make glucose for the cell

• contain a green substance called chlorophyll

whats chlorophyll

• green pigment within the chloroplasts which absorbs sunlight for photosynthesis

• is chlorophyll which makes the plants green

what are the 5 structures inside a prokaryotic cell

1. chromosomal DNA

2. plasmids

3. ribosomes

4. cell membrane

5. cell wall

whats chromosomal dna in prokrayotic cell

its one long circular chromosome which controls the cells activities. It floats free in the cytoplasm

whats are plasmids in a prokaryotic cell

small rings of dna that arent part of the nucleoid

whats magnification

how much larger a displayed image is compared with the original object

whats resolution

how well a microscope can distinguish between two points that are close together

whats the magnifying power of a light microscope

x 2, 000

whats the magnifying power of an electron microscope

x 2,000,000

what are the positives of light microscopes

• easy to use

• relatively cheap

• small so easier to transport

• produce colour images

• can view live specimens

what are the negatives of light microscopes

• light has longer wavelength than electrons = lower resolution

• lower maximum magnification thats not good enough to study sub cellular structures (organelles)

what are the positives of electron microscopes

• have a greater magnification and resolution

• can see details within sub- cellular structures

what are the negatives of electron microscopes

• very expensive

• hard to use - require specialist training

• large - difficult to transport

• black and white images

• only view dead specimens

describe the image produced by an electron microscope

the image is black and white, in 2D or 3D and has a very high magnification and resolution

how has electron microscopy increased our understanding of sub cellular structures

electron microscopes can produce higher-resolution images than regular light microscopes. This allows us to see the sub cellular structures within the cell. for example they allow us to see the internal structures of mitochondria

why is staining used in light microscopes

• some specimens are colourless

• useful to highlight different structures

• increases contrast

how do you prepare a specimen on a slide

• pipette a drop of water onto a clean slide

• use tweezers to place specimen on slide

• add a drop of stain if needed

• place a cover slip on the top and press down so there arent any air bubbles

how do you view a specimen on a light microscope

• clip your slide onto the stage

• select lowest powered objective lens

• focus the specimen using the coarse and fine adjustment knob

• if you need to see your specimen with greater magnification swap to a higher powered objective lens and refocus

whats a on the light microscope

eyepeice lens which you look through to see the image

whats B on the light microscope

clips which hold the slides in place

whats C on the light microscope

coarse adjustment knob

whats D on the light microscope

fine adjustment knob

whats E on the light microscope

high and low power objective lenses which magnify the images

whats F on the light microscope

stage which supports the slide

whats G on the light microscope

lamp which shines light through slide so images can be seen more clearly

how do you calculate the total magnification

total magnification = eyepiece magnification x objective lens magnification

whats the formula to calculate magnification from image size and actual size

image size = actual size x magnification

(I AM formula)

whats the structure of dna

is a polymer made up of two strands wrapped around each other to form a double helix

whats a polymer

large, complex molecules composed of long chains of monomers joined together

what are chromosomes

long molecules of coiled up dna which is divided into short sections called genes

whats a gene

a small section of DNA on a chromosome

each gene codes for a particular sequence of amino acids to make a specific protein

what does a nucleotide contain

a sugar, phosphate group and a base. The base is attached to the sugar

what are the 4 different bases in DNA and how do they pair up

a→t

c→ g

what are enzymes

biological catalysts that speed up the rate of metabolic reactions

what are catalyists

a substance that increases the speed of a chemical reaction without being used up in the process

whats the structure of enzymes

enzymes are proteins that contain an active sight that fits into a specific substrate

what do we call the complex that if formed when an enzyme binds to a substrate

enzyme substrate complex

when were discussing enzymes, what does complimentary mean

s substrate must be complementary to fit the active sight of the enzyme. This means it ‘fits’ the active sight.

what is the special region of the enzyme that binds to the substrate

active sight

whats the lock and key hypothesis for enzyme action

• is a model that explains how enzymes are specific for their substrate.

• It states that an enzyme is specific for its substrate like a key is for its lock.

• substrate has to exactly match the shape of the enzymes active sight for a reaction to be catalysed

what are the 4 factors that affects enzyme function

1. temperature

2. pH

3. substrate concentration

4. enzyme concentration

how does changing the temperature affect an enzyme controlled reaction

• a higher temperature increases the rate at first as the enzyme and substrate move around more so are more likely to meet up and react

• but if it gets too hot the bonds holding the enzyme together start to break

• the active sight starts to change shape

• if it changes shape enough, the enzyme wont be able to bind to the substrate - at this point its been denatured

whats an enzymes optimum temperature

the temperature that gives the highest enzyme activity

whats the effect of the pH on an enzyme

• if the pH is too high or low it interferes with the bonds holding the enzyme together which start to change the shape of the active sight (substrate can still fit but less well)

• active shape changes so much that the substrate cant fit - denatured

whats an enzymes optimum pH

the pH the enzymes work best at

whats the effect of enzyme concentration on the rate of the reaction

• the more enzyme molecules there are in a solution, the more likely a substrate molecule will meet up with it so the rate of reaction increases

• if the amount of substrate is limited theres a point when all the substrates are dealt with so adding more enzyme has no further affect

whats the effect of substrate concentration on the rate of reaction

• the higher the substrate concentration the more likely the enzyme will meet up and react with the substrate

• however once all the active sights are full, adding more substrates makes no difference

whats cellular respiration

a universal chemical process that occurs in all living cells that breaks down glucose to release ATP, which may be used as energy to power many reactions throughout the body.

whats ATP

it stores the energy needed for many cell processes

what type of reaction is respiration

exothermic as cellular respiration is just releasing the energy from the glucose

give 3 examples of how cells use the energy from respiration

• Chemical reactions to build larger molecules from smaller molecules

• Muscle contraction to allow movement

• Keeping warm (to maintain a constant temperature suitable for enzyme activity)

what are the 2 types of respiration

1. aerobic respiration

2. anaerobic respiration

whats aerobic respiration

• the chemical reaction in cells that uses oxygen to break down nutrient molecules to release energy

• complete breakdown of glucose to release a relatively large amount of energy for use in cell processes and reactions

• Carbon dioxide and water are produced as waste products as well as releasing useful cellular energy

how much ATP does aerobic respiration produce

32 ATP

whats the word equation for aerobic respiration

glucose + oxygen → carbon dioxide + water

whats the chemical equation for aerobic respiration

C₆H₁₂O₆ + 6O₂ + 6H₂O → 6CO₂ + 6H₂O (opposite of photosynthesis)

whats anaerobic respiration

• chemical reaction in cells that breaks down nutrient molecules to release energy without using oxygen

• releases much less energy than aerobic respiration as it involves the incomplete breakdown of glucose

• Different breakdown products are formed depending if the process is happening in animals or plants/fungi

how much ATP does anaerobic respiration produce

2ATP

where does anaerobic respiration take place in animals

• muscle cells during vigorous exercise

• When individuals exercise at high intensities, their muscles have a higher demand for energy

• Bodies can only deliver so much oxygen to muscle cells for aerobic respiration

whats the word equatiopn for anerobic respiration in animals

glucose → lactic acid

when do plants need to use anaerobic respiration

• if plants are in waterlogged soil, there is little or no oxygen available

• The plant root cells will respire anaerobically

whats the word equation for anaerobic respiration in plants

glucose →ethanol + carbon dioxide

whats fermentation

• Anaerobic respiration in yeast

• is economically important in the manufacture of bread (where the carbon dioxide produced helps the dough to rise) and in brewing (where the ethanol produced makes beer)

what is oxygen debt

the extra oxygen that is needed to break down the lactic acid formed in anaerobic respiration

what are biological molecules

molecules found in living organisms and are produced by cells

what are nutrients

substances needed for growth, repair and metabolism

what type of molecules are carbohydrates and proteins

polymers

what are carbohydrates made up from

• simple sugars e.g. glucose which are joined in long chains (polymers)to make complex carbohydrates e.g. starch

use the terms polymer and monomer to explain the difference between simple sugars and complex carbohydrates

• complex carbohydrates are large molecules made up of lots of individual smaller molecules called simple sugars

• complex carbohydrates are polymers whilst simple sugars are monomers

how are carbohydrates broken down

the polymer molecules are broken down back into sugars when the chemical bonds between the monomers are broken

what type of enzyme breaks down carbohydrates and where are they found

carbohydrases - found in mouth and small intestine

what are the monomers that make up protein

amino acids

what enzyme breaks down protein back into amino acids and where are they found

Protease - found in stomach and small inestine

what are lipids made up of

fatty acids and glycerol

true of false , lipids are polymers

FALSE - they are not polymers because they dont form a long chain of repeating units

what enzyme breaks down lipids and where are they found

lipase - found in small intestine

what are photosynthetic organisms

the main producers of food and therefore biomass for life on Earth

what type of reaction is photosynthesis

endothermic - energy is transferred from the environment during it

whats the purpose of photosynthesis

for photosynthetic organisms (e.g. green plants and algae) use energy from the sun to make glucose

whats the word equation for photosynthesis

carbon dioxide + water → glucose + oxygen

whats the chemical equation for photosynthesis

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

where does photosynthesis take place

in the chloroplasts

whats the process of phtosynthesis

1. energy transferred by light is used to split water into oxygen gas and hydrogen ions

2. carbon dioxide gas then combines with hydrogen ions to make glucose

whats the experiment to calculate the rate of photosynthesis

• pond weed is places in a test tube full of water

• the top is sealed with bung

• a lamp is placed at a measured distance from the test tube

• count the number of oxygen bubbles coming out of the cut stem in 1 minute

• repeat experiment and record results

• calculate average number of bubbles produced per minute

whats the effect of temperature on photosynthesis

• with an increase in temperature, the rate of photosynthesis also increases

• because reaction is controlled by enzymes, this only continues up till a certain temperature and then the enzymes will denature and the rate of reaction will decrease

whats the effect of light intensity on photosynthesis

the higher the light intensity, the rate of photosynthesis increases

how is the relationship between the light source and the plant inversely proportional

because as the distance between the light source and the plant increases, the light intensity decreases

whats the effect of carbon dioxide concentration on photosynthesis

as carbon dioxide concentration increases, so does the rate of the reaction

what are the limiting factors in photosynthesis

• carbon dioxide, light intensity and temoerature

• in low levels these restrict any increase in the rate of photosynthesis

• despite increases in other factors the rate of photosynthesis will not increase any more