B2b Flashcards
What are enzymes?
Biological catalysts that increase speed of a reaction without being used up. They only catalyse one reaction
What are enzymes made from?
Proteins from amino acids in a unique shape
Why do enzymes need the right conditions?
Wrong temperature or pH breaks bonds so substrate can’t fit in active site, reaction won’t be catalysed (denatured)
What are often the right conditions for enzymes in the human body?
37 degrees
pH7
Why do nutrients need to be digested?
Starch, protein, lipids are big molecules but only small molecules can pass through digestive system walls
What does amylase do and where is it found?
Starch into glucose/ maltose
Mouth, salivary gland, pancreas, small intestine
What does lipase do and where is it found?
Lipids into glycerol + fatty acids
Pancreas, small intestine
What does protease do and where is it found?
Proteins into amino acids
Stomach (pepsin), pancreas, small intestine
What does the liver do?
Produces bile which neutralises stomach acid (which kills bacteria) and emulsifies fats
What do the small and big intestines absorb?
Small - food
Big - water
How do biological detergents work?
Proteases + lipases remove stains like food
They work at lower temperatures
How are enzymes used in food?
Protease - pre-digested baby food
Amylase - starch into sugar syrup
Isomerase - glucose into fructose
What are the advantages of using enzymes in industry?
Specific
Lowers temps and pressure - save money
Last a long time
Biodegradable
What are the disadvantages of using enzymes in industry?
Develop allergies
Conditions must be controlled
Expensive
Contaminations
What is respiration?
The release of energy from glucose that happens in every cell, in the mitochondria
What is the equation for aerobic respiration?
Glucose + oxygen into carbon dioxide + water + energy
What is energy used for in plants and animals?
Building larger molecules e.g. proteins
Muscle contraction (mammals)
Maintaining body temp (mammals + birds)
Build sugars, nitrates to amino acids (plants)
What happens during exercise?
Muscles need more energy
Extra CO2 needs to be removed
Glycogen in every cell converted to glucose
What is anaerobic respiration?
The incomplete breakdown of glucose
Glucose into lactic acid + energy
Why can’t anaerobic respiration be maintained for a long time?
Lactic acid build up is painful + muscle fatigue
Doesn’t release as much energy
What is oxygen debt?
When your body needs to repay the oxygen not used in exercise
O oxidises lactic acid into CO2 and water
What is DNA?
Deoxyribonucleic acid - contains instructions to put organisms together and how they work
What is a gene?
A short section of DNA
How do genes make proteins?
By determining the order of bases (A,C,G,T). Three bases make one amino acid, which make up proteins. The type of protein made determines the type of cell something is
What is an allele?
A different version of the same gene
What can DNA fingerprinting be used for?
Forensic science
Paternity tests
Describe the process of mitosis
Parent cell replicates DNA making X-shaped chromosomes
Chromosomes line up
Cell pulled apart to make two daughter cells
Describe the process of meiosis
A cell replicates DNA, making X-shaped chromosomes that pair up
Cell splits leaving only one of each pair
Cells split again to leave gametes
What is the difference between mitosis and meiosis?
Mitosis produces two identical cells with 46 chromosomes, no pairing occurs, asexual
Meiosis produces four different cells with 23 chromosomes, paring occurs, sexual
What is differentiation?
The process by which a cell changes to become specialised
What are stem cells?
Undifferentiated cell - embryonic stem cells can turn into any type, adult aren’t as versatile
What are the advantages of stem cell research?
1) Cure people + save lives
2) Permanent solution
3) Grow new organs for transplants
4) Improves quality of life
5) Discarded embryo destroyed anyway
What are the disadvantages of stem cell research?
1) Embryos = people = murder
2) Possible risk of cancer
3) Religious beliefs
4) Long term effects
5) Designer babies??
Why did people not accept Mendel’s work straight away?
He had no proof - chromosomes could not be seen
What was Gregor Mendel’s experiment?
Breeding pea plants
First cross - all one characteristic
Second cross - different characteristics
What did Mendel prove?
Characteristics are determined by hereditary units (genes) which could be dominant or recessive
What is the difference between a dominant and recessive gene?
Dominant- only need one copy of allele
Recessive - need 2 copies
What is the difference between genotype and phenotype?
Genotype - combination of alleles
Phenotype - outward appearance
What is the difference between homozygous and heterozygous?
Homo- same genotype
Hetro- different genotype
How do you find dominance or recession in family trees?
Find same parents with different child
Parents must be heterozygous
If parents suffer - dominant
If not suffer - recessive
What is cystic fibrosis?
Genetic disease- recessive allele
Can have carriers
Parents must be sufferers or carriers to have affected children
What is polydactyly?
Extra fingers/ toes - dominant
No carriers
Can be inherited if just one parent has it
What are the advantages of embryo screening?
1) Help stop suffering
2) Laws stop it going too far
3) Embryos destroyed anyway
4) Treating disorders expensive
What are the disadvantages of embryo screening?
1) Pick desirable babies
2) Embryos destroyed
3) Prejudice- genetic problem people bad
4) Expensive
How did life begin?
No one knows - primordial soup, comet etc
Lack of reliable evidence since early organisms soft bodied or fossils destroyed
What are fossils?
The remains of plants and animals
What are the three ways fossils are made?
1) Gradual replacement by minerals where slow decay happens - forms rock-like substance
2) Casts and impressions - when clay hardens around organism
3) Preservation - e.g. Amber + tar pits - no oxygen or moisture, glaciers, peat bogs too acidic
What is extinction?
When a species no longer exists because it could not adapt to its surroundings
What can cause extinction?
Environmental changes
New predator or disease
Can’t compete for food
Catastrophic event
What is a species?
Animals that can breed to produce fertile offspring
What is speciation?
The development of a new species
How does speciation occur?
1) Physical barrier - geographical isolation
2) Slightly different conditions
3) Variation within a species
4) Different characteristics increase chance of survival
5) Better adapted animals pass on favourable genes
6) Variation becomes common
7) Eventually two groups can’t produce fertile offspring
