SB1 - Key Concepts Flashcards
What is magnification
If makes an image look bigger
So a x30 lens would make an object 30 times bigger
How do you work out a microscopes magnification
Multiply the magnification of the 2 lenses together
Multiply the eyepiece lens and objective lens
What’s the resolution
The smallest distance between two points that can still be seen as 2 seperate points
What are electron microscopes like
Instead of light beams passing through the specimen to build up an image
Electron Microscopes can magnify more and have a better resolution than a light microscope
They allow us to see cells with great detail and clarity
Tell me the prefixes
Millimetres (mm)
Micrometres (um)
Nanometres (nm)
Picometres (pm)
Divide by 1000 to to get down a stage eg mm to um
Multiply by 1000 to get up a stage eg micro to milli
What is a cell with a nucleus also described as
Eukaryotic
What is the cell membrane
Is like a very big thin bag
It controls what enters and leaves the cell and seperates one cell from another
What’s the cytoplasm
It contains a watery jelly and it’s where most cells activities happen
What are mitochondria
Are jelly bean shaped structures in which aerobic respiration
Very difficult to see with a light microscope
What’s the nucleus
Controls the cell and its activities
Inside it are chromosomes which contain DNA
Especially large in white blood cells
What are ribosomes
In cytoplasm many round tiny structures make proteins for cell
Impossible to see with light microscope
What is the field of view
The circular area you see in a light microscope
What do electron microscopes allow us to see that light microscopes can’t
Mitochondria
What’s the cell wall
In a plant cell
It’s made of cellulose and supports and protects the cell
What are chloroplasts
In plant cell
Contain chlorophyll which traps energy transferred from the sun
The energy is used for photosynthesis
What’s a vacuole
In plant cells
Stores cell sap to help cell keep firm and rigid
What are specialised cells
They have a sledie if function
About 200 different kinds
They are adapted to their functions
How are the cells adapted in the small intestine lining specialised
They absorb small food molecules produced by digestion
Adapted by having membranes with tiny folds called microvilli
This adaption increase the surface area of the so more molecules can be absorbed, the faster the absorption Happens
How is the pancreas adapted
It makes enzymes needed to digest certain foods in the small intestine
Enzymes are proteins and so these cells are adapted by having a lot of ribosomes
What are gametes
In sexual reproduction, the two specialised cells sex cells, they fuse to create a cell that develops into an embryo
Human gametes are egg cell and the sperm cell
How many chromosomes do most body cells have
Two copies of the 23 different type of chromosome so 46 in total
Gametes one have one copy of each and so 23 each
What are cells with two sets of chromosomes also known as
Diploid
What are cells with one copy of each chromosomes called
Haploid
How is the female egg cell gamete specialised
The jelly coat protects egg cell, it hardens after fertilisation to ensure that only one sperm enters the egg cell
The cytoplasm is packed with nutrients to supply the fertilised egg cell with energy and material for the growth and development of embryo
How is the male sperm cell specialised
It has a streamlined shape to travel
It has a large number of mitochondria are arranged in a spiral around the top of the tell to release lots of energy to power the tail
The tip of the head contains a small Vacuole called the acrosome - it contains the enzymes that break down substances in the eggs cells jelly coat
Allows sperm to
Burrow inside
What happens in fertilisation
Occurs in the oviducts, cells in the lining of oviduct transport cells (or the developing embryos after fertilisation) towards uterus
How are oviduct cells adapted
Have hair like cilia - wave side to side to sweep substances along
What are cells that kind structures in the body also called
Epithelial cells
What are cells that line structures in the body and have cilia also called
Ciliated epithelial cell
How do we look at bacteria
Difficult to see with light microscopes as small and colourless so stains often used
What is the flagellum on a bacteria
A round like propeller so the bacteria can move
Not all bacteria have them
What type of cells are bacteria
Prokaryotic
Cells don’t have nuclei or chromosomes
Don’t have mitochondria or chloroplasts
Instead of a nucleus what does a bacteria contain
One large loop of chromosomal DNA - also smaller loops of DNA called plasmids
What do Plasmids do
Controls a few of the cells activities
Tell me some parts of the bacteria cell
Slime coat for protection (not all bacteria have this)
Flexible cell wall for support which is not made out of cellulose like plants
Cell membrane
Cytoplasm, contains ribosomes which are smaller than eukaryotic ribosomes
Chromosomal DNA
How big is prokaryotic ribosomes
20nm
How many Nanometres In a metre
1 000 000 000nm
You need to know standard form
Check page 11 of text book for info
What do animals use substances for
Energy, growth, development by digesting food inside their bodies
How do bacteria use substances
Release digestive enzymes into environment and then abstain digested good into their cells
What do digestive enzymes turn in to in humans
Large molecules in our food into smaller smaller subunits
The digested molecules are them small enough to be absorbed by small intestine
What do part of protein molecules breakdown to
Amino acids
What do part of starch molecules break down into
Glucose molecules
What do lipid molecules break down to
Fatty acids
What’s synthesis
Using small molecules to build larger molecules
Carbohydrates and proteins are both polymers because they are made of I small molecules or monomers joined in a chain
Happens very slowly - since subunits rarely collide with enough force or right angle to bond
How can synthesis or breakdown (digestion) be sped up
Using a catalyst and in living organisms they are enzymes
Enzymes are biological catalysts - enzymes are a special group of proteins found throughout the body
What are the substances that that enzymes work on called
Substrates
What are the substances produced when a catalyst reacts with a substrate called
Products
Tell me about the enzyme amylase
Found in saliva and small intestine
It breaks down starch to small sugars such as maltose
Tell me about catalase
Found in most cells, especially liver cells
Breaking down hydrogen peroxide made in many cell reactions to water and oxygen
Tell me about starch synthase enzyme
Found in plants
It used for synthesis of starch from glucose
Tell me about DNA polymerase enzyme
Found in nucleus
Used for synthesis of DNA from its monomers
What are chemical reagents
Identify changes in sugars and stuff
How can an iodine solution be used for chemical reagents
Changes from yellow-orange to blue-black colour when in contact with starch
What can benedicts solution be used for in chemical reagents
Change colour when reducing sugars (including glucose and fructose) are present
What can a biuret test be used for
Potassium hydroxide is mixed with a solution of food, 2 drops of copper sulfate solution and changes to purple of protein present
How can fats and oils (lipids) be tested
Using ethanol emulsion test
Food mixed with ethanol and shaken and poured into water and shaken agian
Fats and oils dissolved in ethanol float to surface, forming a cloudy emulsion when left to stand
What do calorimeters do
The amount of energy transferred from biting food to water can be calculated from increase in water temperature
Measures amount of energy in a food by burning it
How is a protein formed
Formed from a chain of amino acids, caused by folding the chain in a sequence of specific amino acids in a chain
What’s the active site
Where the substrate molecule of the enzyme fits at the start of a reaction
Different substrates have different 3D shapes and different enzymes have different shaped active sites
Enzymes can only work with specific substrates
Tell me what happens when substrate molecule enters an enzymes active site
Two different substrate molecules hold the substrate molecules tightly in right position for bonds to form between them and make 1 product molecule
What can the ph or temperature change do to an enzyme
It can affect how the proteins fold up and affect the shape of active site
If the shape of the active site changes too much, the substrate will no longer fit neatly and so the enzyme will no longer catalyse
We say the enzyme is denatured
What’s the temperature at which the enzyme works fastest also
Known as
Optimum temperature
What else beside temperature can affect the rate of an enzymes reaction
Ph - below and above optimum the shape of the active site is changed
concentration of substrate - high concentration most enzymes active sites contain substrate molecules so it’s as fast as it can be
At low concentration, many enzyme molecules have Empty active sites so rate very slow
How is smell spread
Diffusion
Tell me about diffusion
Particles in gases and liquids are constantly moving past eachother in random directions
This causes an overall movement of particles from where there are more of them (higher concentration) to where there are fewer (lower concentration)
What’s a concentration gradient
The difference between 2 concentrations,
Particles diffuse down a concentration gradient
The bigger the difference, the steeper the gradient and faster diffusion occurs
Tell me about diffusion in body
Allows small molecules such as oxygen and carbon dioxide to move in and out of cells
What is partially permeable or semi permeable
A membrane that allows some molecules through and not others
How do cells do diffusion
Their cell membrane are semi permeable and trap large soluble molecules inside cells, water molecules can diffuse through
What’s a more dilute solute concentration
When there are more water molecules on one side of cell membrane and Less on other (more concentrated solution of solute)
What’s osmosis
The diffusion of small molecules of a solvent such as water through a semi permeable membrane
The overall movement of solvent particles will stop when the concentration of solutes is the Same on both sides of membrane
How do you calculate mass change
Osmosis can cause mass change
Work out difference between mass of tissue at start and end (final mass - initial mass)
Divide difference by initial mass
Multiply by 100
A negative answer is a percentage lost
What’s active transport
Cells may need to transport molecules against a concentration or transport molecules that are too big to diffuse through the cell membrane
How is active transport carried out
By transport proteins in cell membranes
The transport proteins capture certain molecules and carry them across the cell membrane
Active process requires energy
What type of processes are osmosis and diffusion
Passive
Do not require an input of energy
