2b) Enzymes and Genetics Flashcards
What causes an Enzyme to become denatured (shape changed) ?
Too high temperature
Too high or too low PH
What is an enzyme?
Proteins (chains of amino acids)
Act as biological catalysts
Speed up the rate if the reaction
Without being changed or used up in the reaction
What is optimum temperature and PH for an enzyme?
Best conditions for an enzyme to work
Temp: 37 degrees Celsius
PH: often 7 (neutral), not always
(E.g. pepsin at PH2 in stomach)
Why do enzymes have a specific shape?
To match the specific reaction it will catalyse
Name 3 digestive enzymes and what they do
Break down big molecules into smaller molecules
Amylase converts starch into sugar
Protease converts proteins into amino acids
Lipase converts lipids into glycerol and fatty acids
What are lipids?
Fats and oils
Where is the enzyme amylase made?
Salivary glands
Pancreas
Small intestine
Where is the enzyme protease made?
Stomach (as pepsin)
Pancreas
Small intestine
Where is the enzyme lipase made?
Pancreas
Small intestine
Where is the bile produced and stored?
Produced in liver
Stored in gall bladder
What does bile do?
Neutralises stomach acid by making conditions alkaline Emulsifies fats (breaks fats into tiny droplets)
Why does bile emulsify fats?
Allows fat to be broken into tiny droplets
Allows fats to have a bigger surface area
Easier for lipase enzyme to digest
Faster digestion
What is absorbed in the large intestine?
Excess water from food
What is the function of the stomach in the digestive system?
It pummels the food with its muscular walls
Produced protease enzyme (pepsin)
Produced hydrochloride acid to kill bacteria and give right PH (2 acidic) for protease enzyme to work
What is the function of the rectum in the digestive system?
Where the faeces are stored before they are excreted through the anus
What is the gullet?
Oesophagus
Define respiration
The process of releasing energy from the breakdown of glucose which goes on in every cell
What is the word equation for aerobic respiration?
Glucose + oxygen > carbon dioxide + water (+energy)
What is the energy released by aerobic respiration used for?
Build up larger molecules from smaller ones (amino acids- proteins)
In animals - allow muscles to contract - allows movement
In mammals and birds - maintain body temperature
In plants - build up sugars, nitrates into amino acids and into proteins
Why does blood have to flow at a faster rate when you increase muscle activity?
Requires more energy
More glucose and oxygen needed for respiration
Extra carbon dioxide needs to be removed from the muscle cells
What is glycogen?
Glucose from food stored in mainly in the liver but also in each muscle
When do we use anaerobic respiration?
When your body can’t supply enough oxygen to your muscles
Why is anaerobic respiration not the best way to convert glucose to energy?
Incomplete breakdown of glucose produces lactic acid
Lactic acid builds up in the muscles which is painful
Causes muscle fatigue as muscles get tired and stop contracting efficiently
Doesn’t release as much energy
What is the word equation for anaerobic respiration?
Glucose > energy + lactic acid
What does having oxygen debt mean?
Lack of oxygen whilst exercising because you resorted to anaerobic respiration
Need to repay the oxygen that didn’t get to your muscles in time as your lungs, heart and blood couldn’t keep up with the demand earlier
Why do you breathe heavily after exercising?
Meet the demand for extra oxygen which then flows through the blood to your muscles to remove the lactic acid by oxidising it to harmless carbon dioxide and water
Outline 2 ways enzymes are used in the home and in industry
In biological detergents - ideal for removing stains, low temperatures
To change foods - proteases Pre-digest baby food, carbohydraaes turn starch syrup into sugar syrup, isomerase turns glucose syrup into fructose
How are enzymes used to change foods?
Proteases Pre-digest baby food
Carbohydrases turn starch syrup into sugar syrup
Isomerase turns glucose syrup into fructose (less fructose can be used which is sweeter - slimming foods/drinks)
What are the advantages of using enzymes in industry?
Specific - only catalyse reaction you want them to
Lower temperatures - lower costs as it saves energy
Work for a long time - only initial cost, can continually use them
Biodegradable - less environmental pollution
What are the disadvantages of using enzymes in industry?
Could develop allergies to the enzymes
Can be denatured even by small increase in temperature
Susceptible to poisoning and changes in PH
Need tightly controlled conditions
Expensive to produce
Contamination
What does DNA stand for?
Deoxyribonucleic acid
Found in nucleus of cells
Made of long molecules called chromosomes
Contains instructions
What is a gene?
A section of DNA
Contains instructions to make a specific protein using amino acids
Name 2 ways DNA fingerprinting is used
Forensic science - crime scenes
Paternity testing
How many pairs of chromosomes are there in a human cell?
23 pairs
What is mitosis?
Cell division
Body cell divided into identical cells to the original
Used to grow or replace cells that have been damaged
Cell reproduces itself by splitting to form two identical offspring
Describe the process of mitosis
DNA spread out into long strings
DNA duplicates to form X-shaped chromosomes with each side an exact duplicate of the other
Chromosomes line up and cell fibres pull them apart
Membranes form around two sets
Nuclei formed in two new cells
How many chromosomes do gametes have?
23 chromosomes each
So that when they fertilise they produce 46
How does sexual reproduction produce variation?
New individual has a mixture of two chromosomes
Inherit features from both parents
What is meiosis?
Cell division
Produced sex cells (gametes) with half the usual number of chromosomes
Describe the process of meiosis?
DNA duplicates - X chromosomes one arm exact copy of other arm
First division - chromosome pairs line up in the centre of the cell
Pairs pulled apart so only one copy of each chromosome
Second division - arms of chromosomes pulled apart
Four gametes produced each with only a single set of chromosomes
In humans where does meiosis occur?
Reproductive organs:
Testes
Ovaries
What is differentiation?
Process by which a cell becomes specialised for its job
What are stem cells?
Undifferentiated cell that can develop into different types of cells depending on what instructions they’re given
What is the 23rd pair of chromosomes labelled as?
XX - female
XY - male
What conclusions did Gregor Mendel reach after experimenting with pea plants?
Characteristics in plants are determined by hereditary units (genes)
They are passed form both parents, one unit from each
Can be dominant or recessive
What are alleles?
Different versions of the same Gene
Define homozygous
If an organism has two alleles for a particular gene that are the SAME
Define heterozygous
If an organism has two alleles for a particular gene that are the DIFFERENT
When can an organism display a recessive characteristic?
Both alleles must be recessive
Homozygous
What is genotype and phenotype?
Genotype - what alleles you have
Phenotype - the actual characteristics you display
What is cystic fibrosis and polydactyl caused by?
CF - Recessive allele
PD - Dominant allele
What is cystic fibrosis?
Genetic disorder of cell membranes
Body produces lots of thick, sticky mucus in air passages and pancreas
What is polydactyl?
Genetic disorder when a baby is born with extra fingers or toes
Isn’t life threatening
Arguments for and against embryonic screening
Desirability Potential life destroyed Could increase prejudice Screening is expensive Will help stop suffering/ healthy Treating disorders costs government a lot of money
What are fossils?
Remains of organisms from many years ago found in rocks
Name 3 ways fossils form in rocks
From gradual replacement by minerals
From cats and impressions
From preservation a in places where no decay happens
Why do species become extinct?
Environment changes too quickly New predator kills them all New disease kills them all Can't compete with other animals Catastrophic event New species develops
Define a species
Group of similar organisms that can reproduce to give fertile offspring
What is speciation?
Development of new species
When populations do the same species become so different that they can no longer breed together to produce fertile offspring
