B1 Flashcards
What are Eukaryotic cells?
Cells that contain genetic material in a nucleus
Animal and plant cells
Larger (10 - 100 micrometers)
What are prokaryotic cells?
Genetic material floats in cytoplasm (no nucleus)
Bacteria
Smaller ( 1-10 micrometers)
What is the function of a nucleus?
▫️To contain genetic material - which codes for a particular protein ( arranged in chromosomes )
▫️to control cell activity
▫️
What is the function of the mitochondria?
▫️ contains enzymes for the site of respiration (aerobic)
What is the function of the cell membrane?
▫️contains receptor molecules for selective control of what enters and exits the cell
What is the function of cytoplasm?
▫️substance in which chemical reactions occur
▫️contains enzymes
What is the function of vacuole?
▫️keeps the cell rigid and upright
▫️contains cell sap
What is the function of Ribosomes?
▫️Site of protein synthesis
What is the function of chloroplast?
▫️site for photosynthesis
▫️contains chlorophyll 🟩 which transfers energy from the sun as light for photosynthesis
What is the function of the cell wall?
▫️Provides strength to the cell
▫️made of cellulose
Name some examples of prokaryotes:
Aka bacteria
🦠salmonella
🦠clostridium botrildum
🦠E- coli
🦠staphylococcus
What is the cell wall made out of in a prokaryote ?
Peptidoglycan
Describe prokaryotic genetic material?
▫️floating freely in the cytoplasm
▫️singular circular (chromosome )
♾
▫️controls cell activities
What are the functions of plasmids?
▫️small loops of extra DNA
▫️normally for things like drug resistance not essential
Why is the function of flagellum?
▫️Tails that allow the cell to move through liquids
What is the function of pilli?
▫️small hairs to attach to structures and transfer genetic material
What is the function of slime capsules?
▫️outmost layer
▫️protect from drying out
▫️helps cells to stick to smooth surfaces
Eyepiece lens
🔹at the very top
🔹used to see image
Objective lens
🔹normally three of them
🔹used to magnify the image
How do you observe cells through a microscope
🔹lower stage
🔹use Objective lens with lowest magnification
🔷first placed onto a slide, sometimes stained
🔹slip placed on top
🔹mounted onto the stage
🔹raise the stage to it’s highest position
🔹turn fine focus knob
What is the difference between fine focus and corse focus?
Corse focus lifts the stage
Fine focus adjusts the amount of light
How does a light microscope work?
Light shone onto object placed on stage .
Then through objective and eyepiece lens
What is total magnification?
Total magnification = objective lens magnification ✖️eyepiece lens
What is the magnification of an object
I A M
Image size = actual size ✖️magnification
Why stain cells ?
🔹as some cells are colourless, easier to observe
🔹to highlight sub cellular structures
What is resolution?
The ability to distinguish between two points that are close to each other
What is magnification?
The degree to which the size of an image is larger than the real object
Transmission electron microscope (TEM)
🔹has a very high magnification
🔹work like a light microscope but pass electrons
Scanning electron microscope (SEM)
🔹produces 3D images
What are advantages of light microscopes?
🔹cheap
🔹easily transportable
🔹can look at living specimens
What are disadvantages of light microscopes?
🔹low resolution ( limited by the wavelength of visible light)
🔹low magnification
🔹staining required to see one specimens
What are disadvantages of an electron microscope?
🔹cannot see living things as needs to be placed in a vacuum
🔹very expensive
🔹not so transportable
🔹requires special skills/ training
What does DNA stand for ?
Deoxyribonucleic acid 🧬
How many chromosomes are in people?
46
23 pairs
Xxxxxxx
What does a chromosome consist of ?
🔺long strands of DNA combined with protein
Describe the structure of a DNA strand:
🔺a polymer made up of nucleotides (monomers)
🔺double helix
🔺anti parallel (2 strands ) joined by bases
What does a nucleotide consist of
Phosphate
Sugar
Base
🟢
/
🟦—-▪️
What are the four bases?
🟦adenine
🟪cytosine
🟥guanine
🟧thymine
What is complementary bases bonding
Base pairs always bonding together in the same formation
🟦 A = T 🟥
🟪 C = G 🟧
What is a gene?
A short length of the DNA molecule .
Each gene codes for a specific sequence of amino acids which make a specific protein
What is transcription?
🟢DNA too big to leave the nucleus
🟢DNA unzips around the gene and complementary base pairs attach forming a sugar phosphate backbone forming m RNA
🟢mRNA detaches and DNA zips back up
🟢goes from nucleus to ribosome
What is translation?
🟢mRNA goes to a ribosome
🟢ribosome reads mRNA ‘s nucleotides in codons(3)
🟢each anti codon reads a specific amino acid brought by tRNA
🟢the amino acids form a chain from peptide bonding creating protein
What is the complementary base bonding of mRNA?
No thymine , instead uracil
🟪c = g 🟧
⬛️ u = a🟥
What are some differences between mRNA and DNA
🟢mRNA is a single strand
🟢DNA is much bigger
🟢mRNA can leave the nucleus
🟢mRNA uses uracil instead if thymine
What are enzymes?
🟤Biological catalyst: sped up reactions without being used up themselves.
🟤Essential for metabolism
🟤Made from proteins
🟤reusable
What do enzymes do to molecules ?
🟤build larger molecules from small ones
🟤break down large molecules into smaller ones
What is an active site?
🟤Place where substrate binds to enzyme .
🟤To form an enzyme substrate complex where the reaction takes place bad products are released from surface of the enzyme.
How does temperature and pH affect enzymes?
Optimum temp = 37°c
Optimum pH = 7
Increases till Ot and then decrease as enzyme denatures
📈📉
What does denaturing mean?
When the active site of an enzyme changes.
Enzyme substrate complex cannot form
Rate of reaction decreases
How does enzyme concentration affect enzymes?
It increase the reaction until there are no more substrates, this suddenly stops the reaction because there are not enough substrate molecules to react with the enzymes
/| / | / | / |
Why do cells need energy?
- Movement
- Thermoregulation
- Biosynthesis eg: protein synthesis
* building larger molecules from smaller molecules
What is cellular respiration
🟠an exothermic reaction
🟠transfers energy from glucose
🟠is always happening
🟠supplies ATP to all living organisms
What is metabolism?
As the chemical processes that occur within a living organism to maintain life
Aerobic respiration
🟠most efficient way of transferring energy
🟠used when there is enough oxygen
🟠happens in plants and animals and bacteria
🟠occurs in mitochondria
What is the word equation of aerobic respiration?
Oxygen + glucose —> carbon dioxide + water + (ATP)
Chemical has a six before everything apart from glucose
What is anaerobic respiration in animals?
🟠Glucose —> lactic acid
🟠When not enough oxygen
🟠takes place in the cytoplasm
Why is anaerobic respiration not preferred?
🟠incomplete breakdown of glucose
🟠lactic acid build up
🟠doesn’t yield as much energy
What is anaerobic respiration in plants & yeast ?
Glucose—> ethanol + carbon dioxide
In yeast it called fermentation , carbon dioxide can be used in baking and ethanol makes alcohol
How are carbohydrates broken down?
🔻enzymes called carbohydrase eg: Amylase
🔻break the carbohydrates into simple sugars
Carbohydrate = substrate
How are proteins broken down?
🔻broken down by protease enzymes
🔻turn into amino acids
How are lipids broken down?
🔻broken down by lipase
🔻into 1 glycerol and 3 fatty acids released into the blood stream
What is photosynthesis?
🟡making glucose from sunlight
🟡endothermic reaction
🟡occurs in the chlorophyll
🟡 carbon dioxide + water —> glucose + oxygen
Where do the reactants for photosynthesis come from?
🟡carbon dioxide diffuses from the stomata
🟡water comes via osmosis in the roots from the soil up the xylem
What is the light dependent phase in photosynthesis?
🟡light splitting the water into hydrogen and oxygen
What is the light independent phase of photosynthesis?
🟡 the carbon dioxide being add to the hydrogen to form glucose
How does the plant use glucose?
🟡used for respiration
🟡used to make cellulose (strengthen cell walls )
🟡made into starch for storage
🟡added to nitrate ions to make protein
🟡turned into fats and oils for storage
How you test a leaf for starch ?
🌱Put the leaf in boiling water
🌱Put it in a boiling tube with ethanol- removes chlorophyll pigment
🌱Dip the leaf in boiling water to soften it
🌱Add iodine solution
✅If starch is present should to to blue/black
How do you test for chlorophyll
🌚De-starch (leave in dark) a variegated plant , so that previous starch does not ruin the results
🌞Place in sunlight
🌱Starch test
✅If positive there should be blue/black areas with white ares
How do you test for light?
🌚De-starch leaf
🌗Make a partially covered leaf
🌱Test for starch
How do you test a leaf for carbon dioxide ?
🌱Place a leaf of the plant in a closed system with soda lime.
🌱This absorbs the carbon dioxide (reactants) which means the photosynthesis won’t happen.
🌱Starch test
✅Leaf should be orange brown as photosynthesis did not happen
How do you test for oxygen?
💦🌿Place the aquatic plant in water
🧪Collect bubbles of the gas
✅Make sure it is oxygen by holding out a glowing split and making sure it is relighted
How are light and distance related?
Light is inversely proportional to the square of the distance:
Light = 1➗distance ^2
What are the limiting factors for photosynthesis, and how do they affect the rate of reaction?
🔮temperature- increase until the enzymes denature
🔮light intensity- increases
🔮carbon dioxide -increases
What is the purpose of simple sugars?
They can go into the blood and provide energy
What is the purpose of amino acids (from digestion of proteins)?
They can be built back up into proteins by protein synthesis
What is the purpose of fatty acids and glycerol ( in the digestion of fat)?
?
What is a limiting factor?
Despite an increase in other factors (eg: temperature/carbon dioxide).
The rate of photosynthesis will not increase any more. This can be seen on the graph as a curve levelling off.
How can you identify a limiting factor on a graph?
The other two conditions will be constant or the same effect to each reactant.
The limiting factor will have a change
How does substrate concentration affect enzymes?
It will increase the rate of reaction until there are enough enzymes,after that it will keep the rate the same
How does the structure of DNA affect the proteins made?
🔵The triplet code (codons)
🔵 used to determine amino acids in proteins
How could you measure the rate of photosynthesis? (Experiment)
Do the oxygen pondweed experiment, count the amount of bubbles produced, in varying factors
