From Big to Small - biological molecules, cells, organisms and kingdoms Flashcards
what are the components of an animal cell?
contain:
- cytoplasm
- nucleus
- ribosome
- mitochondrion
- cell membrane
what are the components of a plant cell?
contain:
- cytoplasm
- nucleus
- ribosome
- mitochondrion
- cell membrane
- chloroplast
- vacuole
- cell wall
what is an organelle?
organelles are small structures which carry out functions (jobs) needed to keep the cell alive.
draw and label a plant and animal cell.
from big to small: picture 1 and 2
what is the function of the nucleus?
- controls the activity of the cell (by making proteins
- contains the chromosomes - strands of DNA which carry the genes (each gene code for a protein).
what is the function of the cell membrane?
- a boundary between the cytoplasm and the cell’s surroundings
- controls what substances enter and leave the cell (selectively permeable)
what is the function of the cytoplasm?
- a jelly-like liquid where chemical reactions occur
what is the function of the mitochondria?
- carries out some reactions of aerobic respiration, producing ATP (energy carrier molecule)
what is the function of ribosomes?
- synthesise (assemble) proteins from amino acids
what is the function of chloroplasts?
- absorb light energy and use it to carry out chemical reactions of photosynthesis, making biological molecules for plant cells.
what is the function of a cell wall?
- made of cellulose (a carbohydrate) in plants
- helps to keep plant cells in a fixed shape (and so keeps the plant upright)
what is the function of a vacuole?
- filled with a watery liquid called cell sap, which stores dissolved sugars, mineral ions and other substances
how many millimetres are there in one metre?
1 x 10^3 mm
how many micrometres are there in one metre?
1 x 10^6 micrometres
how many nanometres are there in one metre?
1 x 10^9 nm
what is the equation for calculating magnification?
magnification = image size / actual size
what are cells?
Cells are the smallest functional unit of life and contain a number of organelles, structures that carry out specific processes the cells needs to survive.
what are tissues?
tissues are groups of similar cells, which work together to carry out the same function (job). an example in humans is muscle tissue.
what are organs?
organs are made up of several different tissues working together to carry out a more complex function. in humans, muscle is one of the tissues making up the heart.
what are organ systems?
organ systems are made up of several different organs working together to carry out a complex function essential to life (e.g. circulating blood around the body)
what is the order of organisation?
cells, tissues, organs, organ systems, organism
what are stem cells?
all cells begin as stem cells, which are not specialised to a particular job, but are able to divide over and over in order to make new cells.
how are specialised cells made?
some stem cells the differentiate (develop new features) to become specialised cells- ones which have the structures and proteins needed to carry out a specific job in the organism.
what are some examples of specialised cells?
red blood cells, sperm cell, palisade (leaf) cell
what is the function of the red blood cell and what are its adaptations (features)?
- function : to transport oxygen in the blood
- features:
- contains the protein haemoglobin- binds to and transports oxygen
- no nucleus - more space for haemoglobin
- biconcave shaped (pinched disc) - larger SA, so oxygen can enter and leave cell more quickly
what is the function of the sperm cell and what are its adaptations (features)?
- function : to transport male genetic material to the egg cell
- features:
- flagellum (tail)- to allow the sperm cell to swim
- many mitochondria - to provide energy needed for swimming
- acrosome- package of enzymes, to digest the jelly layer, surrounding the egg cell
what is the function of the palisade (leaf) cell and what are its adaptations (features)?
- function: to carry out photosynthesis
- features:
- many chloroplasts- to trap light energy for photosynthesis
- tall and thin- cells can pack tightly together so more of the light reaching the leaf is absorbed
what are biological molecules?
All cells are made of a wide range of compounds. By far the most common are water and the biological molecules - carbohydrates, proteins, lipids (fats) and nucleic acids (DNA and RNA). The biological molecules are all large structures, made of smaller units.
what are the 3 biological molecules?
carbohydrates, lipids and proteins
what are the chemical elements of carbohydrates?
- carbon
- hydrogen
- oxygen
what are the uses of carbohydrates?
Carbohydrates are broken down in a chemical reaction, respiration, to release energy in the form of ATP. This energy is used for other reactions and processes in cells.
what are the monomers (smallest units) of carbohydrates?
simple sugars- monosaccharides
what are examples of monosaccharides?
- glucose
- fructose
what can also be made by 2 sugar molecules?
disaccharides
what are examples of disaccharides?
- sucrose
- lactose
- maltose
what are the polymers of carbohydrates?
polysaccharides
what are examples of polysaccharides?
- starch
- glycogen
- cellulose
draw a sketch of the structure of a carbohydrate.
from big to small- picture 3
what is starch used for?
to store glucose in plants
what is glycogen used for?
to store glucose in animals and fungi.
why are starch and glycogen better storage molecules?
as they are less soluble than simple sugars and so have less effect on water movement in and out of cells.
what are the chemical elements in lipids?
- carbon
- hydrogen
- oxygen
what are the uses of lipids?
- energy storage (can also be used in respiration)
- part of cell membranes
- thermal insulation
- electrical insulation (around nerve cells)
- buoyancy- helps marine animals such as whales to float
what is the monomer of lipids?
3 fatty acids joined to a glycerol molecule.
draw the sketch of the structure of lipids.
from big to small : picture 4
what are the chemical elements of proteins?
- carbon
- hydrogen
- oxygen
- nitrogen
what are the uses of proteins?
- growth and repair
- structural molecules (e.g. collagen and keratin)
- controlling chemical reactions - enzymes
- messenger molecules - hormones
- combatting disease - antibodies
- transport - e.g. haemoglobin and cell membrane proteins
- energy storage
what is the monomer of a protein?
amino acids
what is the polymer of a protein?
polypeptide/ protein
how many different amino acids are there?
20, which can be combined in any order, resulting in millions of different protein structures.
describe the experiment for testing for glucose.
BENEDICTS SOLUTION
- add benedict’s solution to a sample of food (in a solution)
- place in a water bath at 80 degrees for 5 minutes
- if glucose is present : blue -> brick red
- if it is green, yellow or orange, it is still a positive result but will have a lower concentration of the sugar
draw a sketch of the structure of a protein.
*from big to small: picture 5
describe the experiment for testing for starch.
IODINE
- add a few drops of orange iodine solution to the sample on a spotting tile
- if starch present: yellow -> blue- black
describe the experiment for testing for protein.
BIURET
- add 2cm^3 of water to a food sample and shake if not already liquid
- add an equal volume of dilute potassium hydroxide and shake
- add two drops of 1% copper sulfate solution
- if protein present: blue -> purple
describe the experiment for testing for lipids.
EMULSION TEST
- the food sample is placed in a test tube
- add a small volume of ethanol and shake to dissolve any lipid in the ethanol
- add an equal volume of water
- shake again
- if lipid is present : clear -> milky white emulsion
what are all chemical reactions which occur in cells controlled by?
a group of proteins called enzymes.
what are enzymes?
biological catalysts
what is a catalyst?
a catalyst is a chemical which increases the rate of a reaction without being used up itself in the reaction. catalysts take part in the reaction but afterwards remain unchanged and so are free to catalyse more reactions. cells contain hundreds of different enzymes, each catalysing a different reaction.
what can we use to describe how enzymes work?
the lock and key theory
describe how enzymes work.
- the substrate and enzyme collide.
- the substrate binds to the active site of the enzyme.
- binding to the active site strains the chemical bonds in the substrate molecules and so the reaction occurs by an alternative pathway with a lower activation energy (the energy needed for a reaction to occur)
- once the reaction has occurred, the products do not fit the active site’s shape as well as the substrate did, so they are released.
- after the reaction the enzyme molecule is free to catalyse the next reaction.
- the active site of a particular enzyme has a specific shape which is complementary to the shape of the substrate(s). this means that each enzyme can only catalyse one reaction.
what affects the rate of an enzyme controlled reaction?
- high temperatures
- changes in pH
- adding more substrate or enzyme (increasing the concentration) will speed up the reaction.
how does temperature affect the rate of an enzyme controlled reaction?
as the temperature increases, the enzyme and substrate have more kinetic energy. they move faster and so there are more successful collisions.
how does pH affect the rate of an enzyme controlled reaction?
all proteins are held together by forces between different parts of the amino acid chain. high temperatures and changes of pH disrupt these forces, so the shape changes.
- we say the protein is denatured
- in enzymes, the active site changes shape so it is no longer complementary to the substrate
how does adding more substrate or enzyme (increasing the concentration) affect the rate of an enzyme controlled reaction?
Adding more substrate or enzyme (increasing the concentration) will speed up the reaction.
what is DNA called?
nucleic acids
what components does DNA have?
- chromosome
- gene
- genome
where is the DNA found in a cell?
the nucleus
draw a diagram to represent DNA.
from big to small: picture 6
what is a chromosome?
a chromosome is a straight (linear) strand of DNA. Most cells contain 2 pairs of chromosomes - 2 strands with the same genes.
how many chromosomes do most cells contain?
2 pairs - 2 strands with the same genes.
what is a gene?
a gene is a short section of DNA within a chromosome- it codes for a specific protein (which gives us characteristics)
what is a genome?
a genome is the total DNA of an organism- coding for all its characteristics.
what is DNA?
DNA is the chemical which contains the information for making proteins- it contains the instructions for all the structures and reactions needed in all the cells of an organism.
describe the structure of DNA.
- double stranded molecule - made of two chains of nucleotides
- the strands coil to form a double helix
what is a nucleotide formed of?
- a sugar (deoxyribose)
- phosphate
- nitrogenous base
what are the four bases of a DNA?
- adenine
- thymine
- cytosine
- guanine
what do the bases in the nucleotide form?
complementary pairs which join the 2 sugar-phosphate backbones together:
- adenine -> thymine
- cytosine -> guanine
what does the sequence of triplets of bases provide?
instructions for the sequence of amino acids in a protein.
draw the structure of a chain of nucleotides.
from big to small: picture 7
what are the 5 kingdoms?
- plants
- animals
- fungi
- protoctista
- bacteria
which of the 5 kingdoms are eukaryotic?
- plants
- animals
- fungi
- protoctista
which of the 5 kingdoms is prokaryotic?
- bacteria
what are eukaryotes?
organisms whose cells contain a proper nucleus- a membrane sphere containing linear chromosomes of DNA. they all also have other organelles with outer membranes, such as mitochondria.
describe the plant kingdom.
- all multicellular- made of many (specialised) cells
- make their own complex biological molecules by photosynthesis
- cells have:
- chloroplasts- for photosynthesis
- cellulose cell wall - store carbohydrates as starch or sucrose
- not pathogenic
what are examples of plants?
daffodil, apple tree, sunflower
describe the animal kingdom.
- all multi-cellular - made of many (specialised) cells
- eat other living things to obtain nutrients (biological molecules)
- cells do not have chloroplasts or a cell wall
- store carbohydrates as glycogen
- have a nervous system for coordination and movement
- not pathogenic
what are examples of animals?
lions, tigers, giraffes
describe the fungi kingdom.
- mostly multi-cellular - consist of threads of cells called hyphae. hyphae bunch together to form mycellium
- some have a reproductive structure- mushroom/toadstool
- feed by saprotrophic nutrition
- cells have:
- no chloroplasts
- chitin cell wall
- many nuclei per (large) cell - store carbohydrates as glycogen
- pathogenic
what are examples of fungi?
- yeast (unicellular)
- mucor: typical hyphal structure- millions of hyphae -> mycellium
what is saprotrophic nutrition?
the extracellular secretion of digestive enzymes.
describe the protoctista kingdom.
- all uni-cellular
- some photosynthesise and others feed on living organisms or organic remains
- cells can have:
- chloroplasts- for photosynthesis
- cell wall
- flagella for movement - lots of variation
- pathogenic
what are examples of protoctista?
- amoeba - feed on other living organisms
- chlorella - photosynthetic
- plasmodium- the protoctista which causes malaria
describe the bacteria kingdom.
- small uni-cellular organisms
- do not have a proper nucleus, instead the genetic material is in the cytoplasm in the form of a single circular chromosome
- have a cell membrane, controlling what enters and leaves the cell
- have a cell wall made of peptidoglycan - a complex molecule of sugars and proteins which maintains shape and protects the cell
- has cytoplasm, containing circular chromosome, where chemical reactions occur
- some bacteria have:
- a slime capsule, outside the cell wall and providing more protection
- a protein coat
- plasmids, small circles of DNA containing extra genes
- flagellum, which allows the bacteria to move - pathogenic
- some bacteria feed by saprotrophic nutrition
what are pathogens?
microorganisms which cause infectious disease and harm the host by releasing toxins or damaging cells.
what are examples of bacteria?
- lactobacillus - breaks down milk sugars and is used in yoghurt production
- pneumococcus - pathogenic and is one of the causes of pneumonia (lung infection)
describe viruses.
- a strand of genetic material (DNA or RNA), surrounded by a protein coat
- not cells and are not alive, do not respire, or carry out any of the other normal processes taking place in living organisms.
- to reproduce, they enter a host cell, take over the ribosomes and enzymes in the cell to make new virus particles. when many new viruses have been made, the cell dies and the viruses are released to infect new cells
- all pathogens
draw the internal structure of a bacterium.
from big to small: picture 8
what are examples of viruses?
- Tobacco Mosaic Virus - causes brown patches on leaves by stopping chloroplast production
- Influenza - infects humans causing a cough and temperature
draw the internal structure of a virus
from big to small: picture 9
explain saprotrophic nutrition.
decomposers (fungi and some bacteria) feed by saprotrophic nutrition.
- they secrete dead enzymes outside of their cells onto the dead organism
- the dead organism is broken down into small, soluble molecules which are then absorbed by the decomposer.
biological consequences of smoking on lungs.
- emphysema -> damage to alveoli -> flattens and reduces elasticity -> less SA -> slows the rate of gas exchange
- bronchitis -> bacteria -> cilia cells damaged by the tar in a cigarette -> build-up of mucus which cannot be wafted out
- cancer -> carcinogens -> causes genetic mutations in nucleus of cells.
