⭐️SB1 - Key Concepts In Biology Flashcards
Describe the most common microscope used today
Has two lenses, was invented at the end of the 16th century by Hooke and had a magnification of x30
How do you find a microscopes magnification?
You multiply the magnification of the two lenses:
Eyepiece lens x objective lens
What microscope came after Hooke’s?
One with magnifications of up to x270 by Leeuwenhoek as he constructed single lens microscopes with much better lens quality
What is the resolution?
The smallest distance between two points that can still be seen as two points
What can the best microscopes magnify up to today?
X1500 due to stains, better lenses and light sources
What is the electron microscope?
Invented in the 1930s uses electrons to pass through a specimen and build up an image instead of light, they magnify up to 2 million with resolutions of 0.0000002 to see cells with great detail and clarity
What are all the measurements and how do they increase and decrease?
Millimetre🔻divide by 1000
🔺x by 1000 Micrometer🔻divide by 1000
🔺x by 1000 Nanometer🔻divide by 1000
🔺x by 1000 Picometer
What is a eukaryotic cell?
A cell with a nucleus
What does the cell membrane do?
Controls what enters and leaves the cell
What does the cytoplasm do?
Contains a water jelly and is where cells activities occur
What do the mitochondrion do?
Jelly bean shaped structures where aerobic respiration occurs
What does the nucleus do?
Controls the cell and it’s activities. Stores chromosomes which contain DNA
What are ribosomes?
Name proteins for new cells in the cytoplasms
What is the field of view?
Circular area you see in a light microscope
What do animal cells and plant cells contain?
Cell membranes, cytoplasm, mitochondrion, nucleus, chromosomes and ribosomes
What additional structures do plant cells have?
Cell wall, chloroplasts and chlorophyll and the vacuole
What is the cell wall?
Made of cellulose and supports and protects the cell
What are chloroplasts?
Contain chlorophyll which trap energy transferred from the sun used for photosynthesis
What is a vacuole?
Stores cell sap and helps keep the cell firm and rigid
What are specialised cells?
Cells that have a specific job and are adapted to their functions
What are epithelial cells in the intestines
Cells that line the small intestine and absorb food molecules produced by digestion
How are epithelial cells adapted?
They have membranes with many tiny folds (microvilli) and increase cell surface area so more molecules can be absorbed and so absorption is sped up
How is the muscle cells in the wall of the small intestine adapted to its function?
The muscle cells need to squeeze food along it which requires a lot of energy so they have a lot of mitochondrion
How are cells in the pancreas adapted?
They have a lot of ribosomes as the enzymes they need to make are proteins
How is an egg cell adapted to its function?
- Has 23 chromosomes -haploid (half the needed amount)
- after fertilisation, the cell membrane hardens to prevent other sperm cells entering
- cytoplasm is packed with nutrients to supply the fertilised egg cell with energy and raw materials for embryo growth
How is a sperm cell adapted to its function?
- tip of head contains a small vacuole called the acrosome and contains enzymes to break down jelly coat of egg
- streamlined shape
- large number of mitochondria to release energy to power the tail
- has a tail to allow the sperm to swim
How are oviduct cells adapted for their function?
Contain Celia which wave from side to side and can sweep structures along
How can bacteria show up on a light microscope?
With use of stains
What does it mean if bacterias are prokaryotic?
They don’t have a nucleus or chromosomes
What structures do bacterium contain?
- Flagellum (not in all bacteria)
- chromosomal DNA
- plasmids
- slime coat
- flexible cell wall
- cytoplasm
- cell membrane
What is a slime coat for in bacteria?
For protection but not all have this
What is flagellum for in bacteria?
Spins like a propeller so the bacteria can move
What does bacteria’s chromosomal DNA do?
Controls most of the cells activities
What are plasmids in bacteria?
They are smaller loops of DNA which control a few of the cell activities
How do bacteria get substances for energy, growth and development?
By releasing digestive enzymes into their environments and then absorbing the digested food into their cells
What do digestive enzymes do to large molecules?
Turn them into the smaller subunits they are made of
What does protein starch and lipids break down to?
Protein - amino acids
Starch - glucose
Lipids - fatty acids
What is synthesis?
Building larger molecules from smaller subunits
What are monomers?
The smaller molecules that make up polymers
What does a catalyst do?
Speed up reactions and in living organisms, these catalysts are enzymes making them biological catalysts
What are enzymes
a special group of proteins that are found throughout the body
What are substrates?
The substances that enzymes work on and the substances they produce are the products
Describe amylase
An enzyme found in saliva and small intestines and is responsible for breaking down starch to smaller sugars like maltose
What is catalase?
An enzyme found in most cells but especially liver cells. It breaks down hydrogen peroxide made of many cell reactions to water and oxygen
What is starch synthase?
A plant enzyme responsible for the synthesis of starch from glucose
What is DNA polymerase?
An enzyme found in the nucleus of a cell responsible for the synthesis of DNA from its monomers
Why do bananas taste sweeter as they ripen?
As the starch is broken down by enzymes into smaller carbohydrates including sugars like glucose.
How can we use iodine solution?
To test for starch as when starch is present, it goes from yellow-orange to blue-black
How do you test for reducing sugars?
With Benedict’s solution. You put the food and the solution in s hoy water bath for a few mins and if reducing sugars are present, a reduction reaction happens causing the solution to change colour
How does Benedicts solution change colour?
It starts as light blue, turns darker green if there is very little reducing sugar and then becomes more red with the more reducing sugar
What is the biuret test for?
Protein, by mixing potassium hydroxide with a solution of food and adding two drops of copper sulphate. If the solution goes from pale blue to purple, protein is present
What does the ethanol emulsion test do?
Tests for lipids by mixing the food with ethanol, shaking it, pouring some of the mixture into water and then shaking it again. The lipids dissolved in the ethanol float to the surface forming a cloudy emulsion
What happens if purple solution is formed in a buiret test?
Then protein is present
What does a calorimeter do?
Measures the amount of energy in food
How does a calorimeter work?
Food is set alight under a beaker of water that has a thermometer inside it. After stirring the water, the amount of energy in the food transferred to the water can be found by calculating the increase in water temperature
What is a protein?
A chain of amino acids that has a 3D shape depending on the sequence of amino acids which effects how the chain folds
What is the active site?
The small pocket within the 3D shape of an enzyme where the substrate fits perfectly at the start of the reaction
Why is the active site a different shape for every enzyme?
Every enzyme can only work with a specific substrate
What does the active site do to the substrate?
Holds the substrate molecules tightly in the right position for bonds to form between them and make a product molecule
It’s a significant about the shape of the product molecule?
It is a slightly different shape to the substrate molecules so it’s no longer fits tightly in the active site and is released
What effects how a protein folds up?
Changes in Ph or temperature as they change the shape of the active site
What does it mean when an active site is denatured?
It means the active site changes shape too much and the enzyme will no longer catalyse the reaction
Why is our body kept at a constant temperature?
As that is the optimum temperature for enzyme activity
How do calculate the mean rate of reaction?
The amount of substance broken down by the enzyme divided by the time
Why do enzymes work slowly below optimum temperature?
Because molecules aren’t moving fast enough to Bump into enzyme molecules
Why is there a search for enzymes of high temperature?
Enzymes are used in industrial processes some of which take place at very high temperatures
What is diffusion?
The movement of any gas and liquid particles from an area of high concentration to an area of low concentration without a semi permeable membrane
What is osmosis?
The movement of solvent particles from an area of high water concentration to low water concentration through a semi permeable membrane
How do you calculate the % change?
(Final mass - initial mass)/initial mass
And multiply that answer by a hundred
What is active transport?
The movement of molecules against the concentration gradient causing it to require energy as the molecules move from low concentration to high
What is active transport carried out by?
Transport proteins in cell membranes
Give two passive processes
Osmosis and diffusion as they don’t require an output of energy
