Flashcards in T1 - Key Concepts in Biology Deck (78):
Definition of cell
The building blocks of every organism in the planet
2 types of cells
Eukaryotic and prokaryotic
Complex cells (including plant and animal cells)
Smaller and simpler cells (including bacteria)
Organisms that are made up of eukaryotic cells
Prokaryotic (single cell organisms)
Subcellular structure of an animal cell
Contains genetic material that controls the activities in the cell. Genetic material is arranged into chromosomes
Gel like substance where most of the chemical reactions happen. It contains enzymes that control these chemical reactions
Holds the cell together and controls what goes in and out
These are where most of the reactions for respiration takes place. Respiration transfers energy that the cell needs to work
These are involved in the translation of genetic material in the synthesis of proteins
What are the extra things that plant cells have and animal cells don’t?
Made of cellulose, it supports the cell and strengthens it
Contains cell sap, a weak solution of sugar and salts. It maintains the internal pressure to support the cell
These are where photosynthesis occurs which makes food for the plant. They contain a green substance called chlorophyll
Subcellular structure of a bacterial cell
Hollow hair like structures made of protein allow bacteria to attach to other cells to transfer genetic information
One long circular chromosome which controls the cells’ activities and replication. It floats free in the cytoplasm
Small loops of extra DNA that aren’t part of the chromosome. Plasmids contain genes for things like drug resistance and can be passed between bacteria
Flagellum (pl flagella)
A long hair like structure that rotates to make the bacterium move. It can be used to move the bacteria away from harmful substances like toxins and towards good things like nutrients or oxygen
Contain lots of different types of cells (ie cells with different structures)
Cells that have a structure which makes them adapted to their function
Examples of specialised cells
Haploid cell (in sperm and egg cell)
Both the nucleus of an egg and sperm cell only contain half the number of chromosomes that’s in a normal body cell
Main functions of an egg cell
Carry the female DNA
Nourish the developing embryo in the early stages
How is the egg cell adapted to its function?
It contains nutrients in the cytoplasm to feed the embryo
It has a haploid nucleus
Straight after fertilisation, it’s membrane changes structure to stop any sperm getting in (so the offspring will have the right amount of DNA)
What is the function of a sperm cell?
To transport the make DNA to the female’s egg
How is the sperm cell adapted to its function?
Long tail to swim to egg
Lots of mitochondria in the middle section to provide energy needed to swim
Has an acrosome at the front where it stores enzymes needed to digest its way through the membrane of the egg
Function of an epithelial cell
Line the surface of organs
Function of ciliated epithelial cells
How is the ciliated epithelial cells adapted to its function?
It has cilia (hair like structures) which beat to move substances in one direction along the surface of the tissue
Example of ciliated epithelial cells?
The lining of the airways where they help to move mucus up to throat so it can be swallowed and doesn’t reach the lungs
Use lenses to magnify things such as cells and increase the resolution of an image
How well a microscope distinguishes between two points that are close together (higher resolution means that an image can be seen more clearly and in more detail)
Invented in the 1590s
They work by passing light through a specimen
They let us see things like nuclei and chloroplasts and we can also use them to study living cells
Invented in the 1930s
They use electrons rather than light
Have a higher magnification and resolution
What is the equation for magnification?
Magnification = image size / real size
(The sizes have to be in the same units !!!!!)
Substance which increases the speed of a reaction, without being changed or used up in the reaction
Why do chemical reactions need to be carefully controlled?
To get the right amounts of substances
How can you make a reaction happen more quickly?
Molecule changed in the reaction
The part where it joins on to its substrate to catalyse the reaction
How many substrates do enzymes usually work with?
1 - said to have high specificity for their substrate
‘Lock and key’ mechanism
For the enzyme to work, the substrate has to fit into the active site. If the substrate’s shale doesn’t match, the reaction won’t be catalysed
What are the 3 things that affect the rate of a reaction?
What happens if the reaction gets too hot?
Some bonds holding the enzyme together will break. This changes the shape of the enzyme’s active site so the substrate won’t fit any more (denatured enzyme)
The temperature that enzymes work best at
What happens if the pH is too high or too low?
The pH interferes with the bonds holding the enzymes together, this changes the shape of the active site and denatures the enzyme
The pH that enzymes work best at. It’s often neutral (pH7) but not always eg pepsin (enzyme that breaks down proteins in the stomach) works best at pH2 so it’s well suited to acidic conditions
How does increasing the substrate concentration increase the speed of reaction?
Because it’s more likely the enzyme will meet up and react with a substrate molecule. But, when all the active sites are full, adding more will make no difference
Rate of reaction
How fast / how much something changes over time
Equation for rate of reaction
Rate = amount it has changed by / time taken
Name 3 big molecules
Proteins, lipids, carbohydrates
Why do organisms need to break big molecules down into smaller components?
Easier to digest
Respiration in plants
What is the name of the enzyme that breaks carbohydrates into simple sugars?
What is the name of the enzyme that breaks down starch?
What is the name of the enzymes that convert proteins into amino acids?
What’s the name of the enzyme that converts lipids into glycerol and fatty acids?
What happens to the pH when lipids are broken down?
The fatty acids will lower the pH of the solution they’re in
How can organisms synthesise carbohydrates and proteins?
Carbohydrates - joining simple sugars
Proteins - joining amino acids
What solution is used to test for sugars?
What solution is used to test for starch?
What test is used to test for lipids?
What test is used to test for proteins?
If starch is present, what will the colour will be?
If starch is not present, what will the colour be?
If there are lipids present, what colour will the solution be?
Milky colour, more lipid = more milky colour
If there’s no protein present, what will the colour of the solution be?
If there is protein present, what colour will the solution be?
An experiment where food is burnt to see how much energy it contains
Equation for how many joules of energy the food contains
Energy in food (J) = mass of water (g) x temp. change in water (degreesC) x 4.2
Equation for the energy per gram of food
Energy in food (J) / mass of food (g)
Gradual movement of particles from places where there are MORE to LESS
What states does diffusion occur in?
Liquid and gas
Movement of water molecules across a partially permeable membrane from a region of HIGH WATER CONCENTRATION to a region of LOW WATER CONCENTRATION
Partially permeable membrane
Membrane with very small holes in so only small molecules such as water can pass