2b Flashcards
What is an enzyme?
A biological catalyst
Define catalyst
A catalyst is a substance which increases the speed of reaction, with ought being changed or used up in the reaction
Why do enzymes have special shapes?
So they can catalyse reactions
What do chemical reactions usually involve?
Things either being split apart or joined together
Why can enzymes generally only catalyse one reaction?
Every enzyme has a unique shape that fits onto the substance involved in a reaction, the substance has to fit its special shape
What two things do enzymes need?
The right temperature and pH
What happens if an enzyme gets too hot?
Higher temperature increases the rate at first. But if it gets too hot, some of the bonds holding the enzyme together break. This destroys the enzymes’s special shape and so it won’t work any more. Its said to be denatured
What happens if the pH of an enzyme is too high or too low?
The pH interferes with bonds holding the enzyme together. This changes the shape and denatures the enzyme
What are the five main parts of the digestive system?
Glands, the stomach, large intestine, small intestine, liver
What do digestive enzymes do?
Break down big molecules into smaller ones
Name three examples of BIG molecules
Starch, proteins and fats
Name four examples of smaller molecules
Sugars, amino acids, glycerol and fatty acids
Why do big molecules need to be broken down into smaller molecules in the digestive system?
So that they can pass easily through the walls of the digestive system
What does amylase do?
Converts starch into sugars
What three places is amylase made?
The salivary glands, the pancreas, the small intestine
What does protease do?
Converts protein into amino acids
What three places is protease made?
The stomach, the pancreas, the small intestine
What does lipase do?
Converts lipids into glycerol and fatty acids
What two places is lipase made?
The pancreas, the small intestine
What are lipids?
Fats and oils
Where is bile produced and stored?
Produced in the over, stored in the gall bladder
What does bile do?
Neutralises the stomach acid and emulsifies fats (breaks the fat into tiny droplets
What are the three main functions of the stomach?
Pummels the food within muscular walls, produces protease enzyme, produces hydrochloric acid
Why does the stomach produce hydrochloric acid?
To kill bacteria, to give he right pH for the protease enzyme to work
What does the pancreas do?
Produced protease, amylase and lipase enzyme. Releases this into the small intestine
What does the small intestine do?
Produces protease, amylase and lipase enzymes to complete digestion
What does the large intestine do?
It is where excess water is absorbed from food
What does the gall bladder do?
Where bile is stored before released into small intestine
What does the liver do?
Where bile is produced
What do the salivary glands do?
These produce amylase enzyme in the saliva
What is respiration?
The process of releasing energy from glucose which goes on in every cell
What is aerobic respiration?
Respiration using oxygen
What is the word equation for aerobic respiration?
Glucose + oxygen = carbon dioxide + water + energy
Name four things that the energy release in aerobic respiration is used for
To build up larger molecules, allow muscles to contract, keep body temperature steady and in plants to build sugars and nitrates into amino acids, which are then built up into proteins
What does physical activity do to you?
Increases your breathing rate and makes you breathe more deeply to meet the demand for extra oxygen, increases the speed at which the heart pumps
How is some glucose from food stored?
As glycogen
During vigorous exercise muscles use glucose rapidly, so what has to happen?
Some of the stored glycogen is converted back to glucose to provide more energy
When is anaerobic respiration used?
If theres not enough oxygen to supply to you muscles
What is the word equation for anaerobic respiration?
Glucose = energy + lactic acid
Name one advantage and two disadvantages of anaerobic respiration
You can keep you muscles going on for longer however it causes lactic acid build up, muscle fatigue and does not release nearly as much energy as aerobic respiration
What is oxygen debt?
Having to “repay” the oxygen that you didn’t get to your muscles during exercise afterwards, have to carry on breathing hard after you stop
Name two uses of enzymes in industry
Biological detergents, change foods e.g. baby foods (easier to digest)
Name two advantages and two disadvantages of using enzymes in industry
Work for a long time (can continually use them), Using lower temperatures and pressures means a lower cos as it saves energy however conditions have to be tightly controlled (denatured) and can be expensive to produce
What is a chromosome?
Really long molecules of DNA
What is a gene?
A section of DNA
How do cells make proteins?
By stringing amino acids together in a particular order
What is DNA fingerprinting?
Cutting up a persons DNA into small sections and then separating them.
What is DNA fingerprinting used for?
Forensic science, paternity testing
What is mitosis?
When a cell reproduces itself by splitting to form two identical offspring
What kind of reproduction uses mitosis?
Asexual reproduction e.g. strawberry plants
In cell division by mitosis, are the new cells varied or identical?
Identical, there is no variation
What is meiosis?
Meiosis produces cells which have half the normal number of chromosomes
How many chromosomes do gametes have?
23 chromosomes each
How many chromosomes do human body cells have?
46 chromosomes
In humans, where does meiosis only happen?
In the reproductive organs
What can embryonic stem cells turn into?
Any type of cell
Why are some people against stem cell research?
Potential human life, should find other source of stem cells
What chromosomes do all men have?
An X and a Y chromosome: XY
What chromosomes do all women have?
Two X chromosomes: XX
What is the probability of getting a boy to a girl?
50:50
What did Mendel show through his genetic experiments with peas?
The height characteristics in pea plants was determined by separately inherited ‘hereditary units’ passed on from each parent. Ratios in offspring showed that unit for tall plants, T, was dominant over dwarf, t
What three important conclusions did Mendel reach?
Characteristics determined by ‘hereditary units’, passed on from each parent, can be dominant or recessive
What is an allele
Different versions of the same gene
If an organism has two alleles for a particular gene the same, what is it?
It is homozygous
If an organism has two alleles for a particular gene that are different, what is it?
It is heterozygous
What is a genotype?
What alleles an organism has
What is a phenotype?
The actual characteristic an organism has
Is Cystic Fibrosis caused by a dominant or a recessive allele?
Recessive
Is Polydactyly caused by a dominant or a recessive allele?
Dominant
What is Embryonic screening?
During IVF before being implanted its possible to remove a cell from each embryo and analyse its genes, can check for genetic disorders
Give two points for and against embryonic screening
For: prevents suffering, saves money treating disorders
Against: designer baby, implies people with genetic problems are undesirable
What are fossils?
The remains of organisms from many years ago, which are found in rocks
What are the there ways that fossils can be formed?
Gradual replacement by minerals, from casts and impressions, preservation in places where no decay happens
How are most fossils formed?
Gradual replacement by minerals e.g. teeth, shells and bones
Give an example of fossils from casts and impressions
A footprint in clay, clay hardens around it, leaving a cast of itself
Give an example of fossils from preservation in places where no decay happens
In amber and tar pits theres no oxygen or moisture so decay microbes can’t survive
Name six reasons why species become extinct
Environmental change, new predator, new disease, can’t compete with other species for food source, catastrophic event, new species develops instead (speciation)
What is speciation?
The development of a new species
When does speciation occur?
When populations of the same species become so different that they can no longer breed together to produce fertile offspring
What two things can lead to speciation?
Isolation and natural selection
What is isolation?
Where populations of a species are separated, can be due to a physical barrier
Explain how speciation due to isolation occurs
Conditions on either side the geographical barrier will be different, populations adapt to environments and natural selection occurs, development of new species
