Topic 2 Genes and health Flashcards
Describe the role of the tRNA in the production of the protein part of a glycoprotein. (2)
-Each tRNA brings a specific amino acid to the ribosome.
-The tRNA with the complementary anticodon binds to the mRNA codon.
-tRNA binds to the ribosome.
Compare and contrast the processes of transcription and DNA replication . (4)
-Both involve the formation of phosphodiester bonds.
-Both involve DNA helicase unzipping the DNA.
-Transcription uses RNA nucleotides whereas DNA replication uses DNA nucleotides.
-Transcription uses RNA polymerase whereas DNA replication uses DNA polymerase.
-Transcription produces a single strand of mRNA whereas DNA replication produces double stranded DNA.
What is a gene? (2)
-A sequence of bases in DNA.
-That codes for a polypeptide.
Explain how a change of one amino acid may lead to a change in structure and properties of the haemoglobin protein. (3)
-Different sequence of amino acids.
-A different amino acid will have a different R group.
-Therefore tertiary structure will change.
-Meaning haemoglobin may not bond to oxygen.
Leptin is a protein. Describe the role of tRNA in the production of leptin. (3)
-tRNA molecules transport amino acids to the ribosomes.
-tRNA molecules has an anticodon that binds to a codon on the mRNA.
-Each tRNA carries a particular amino acid.
Describe how an insertion or removal of 1 or 2 nucleotides from a gene result in the production of leptin with a variety of shorter primary structures. (2)
-Adding or removing 1 or 2 nucleotides changes the triplet code.
-Introducing a new stop codon.
-Coding for a shorter sequence of amino acids.
Describe how mRNA is synthesized at a template strand of DNA. (2)
-RNA aligns with complementary bases on DNA.
-RNA polymerase joins together free RNA nucleotides.
Describe the differences between the structure of DNA with the structure of RNA. (3)
-DNA is double stranded whereas RNA is single stranded.
-DNA contains deoxyribose whereas RNA contains ribose.
-DNA contains Thymine whereas RNA contains uracil.
Describe how nucleotides join together to form DNA. (2)
-Condensation reaction.
-Phosphodiester bonds form.
-DNA polymerase.
Explain why substitution of a base affects the function of a haemoglobin molecule. (3)
-One triplet code is affected.
-Meaning there could be a change in an amino acid.
-Causing tertiary structure to change.
-Haemoglobin would no longer be able to bind to oxygen.
Describe the role of CFTR protein in ensuring that the mucus produced in the lungs is the right consistency. (3)
-Chloride ions leave cells through CFTR channel protein.
-Sodium ions then leave following chloride ions.
-Increasing solute concentration in mucus.
-Water moves out of cells into mucus via osmosis.
Describe roles of transcription and translation in synthesis of a globular protein by a muscle cell. (5)
-The sequence of DNA for globular protein is transcribed.
-Complementary base pairing between RNA nucleotides and DNA to produce mRNA.
-mRNA leaves nucleus and attaches to ribosome.
-Pairing between codons on mRNA and anticodons on tRNA.
-tRNA provides specific amino acids.
-Sequence of bases determines sequence of amino acids.
State where transcription occurs in animal cells. (1)
-Nucleus.
Betalains are large polar molecules. Explain why they can’t move through intact cell membrane. (3)
-Betalain molecules are too large to move through the cell membrane.
-No carrier/channel proteins for betalain molecules to move through.
- Betalain molecules are polar and are repelled by hydrophobic fatty acid tails.
Compare and contrast diffusion and active transport as methods for molecules entering the cell. (3)
-Both move molecules through phospholipid bilayers.
-In both, molecules can move through proteins.
-Diffusion occurs down a concentration gradient, whereas active transport occurs against a concentration gradient.
-Diffusion doesn’t require ATP whereas active transport does.
Compare and contrast exocytosis and endocytosis . (3)
-Both processes involve vesicles.
-Both processes involve energy from ATP.
-Exocytosis moves molecules out of cell whereas endocytosis moves molecules into cell.
-Exocytosis involves vesicles fusing with cell surface membrane whereas endocytosis involves the formation of vesicles.
Describe how glucose molecules moves into the cell. (2)
-Facilitated diffusion.
-Through carrier proteins.
One function of glycoproteins found in cell surface membrane. (1)
-Act as receptors on cell surface membrane.
Explain how phospholipids form a cell surface membrane. (3)
-Hydrophilic head associates with water.
-Hydrophobic tail repels water.
-Bilayer forms with hydrophobic tail pointing towards centre of bilayer.
Describe the function of carrier proteins in a cell surface membrane. (4)
-Involved in facilitated diffusion.
-Movement of large molecules.
-From high concentration to low concentration.
-Involved in active transport.
-Needs ATP to move molecules against concertation gradient.
Describe why single celled organisms don’t need a specialised gas exchange surface. (2)
-Can rely on diffusion to uptake oxygen.
-Large SA:V ratio.
-Short diffusion distance.
Describe structure of cell surface membrane. (3)
-Cell membrane made up of phospholipids and proteins.
-Phospholipids form a bilayer.
-Proteins float in phospholipid bilayer.
-Proteins may span bilayer or be located in only one layer.
Explain how the structure of human lungs enables rapid gas exchange. (4)
-Many alveoli provide a large SA:V ratio.
-Alveoli and capillaries have one cell thick walls meaning they have a short diffusion distance.
-High concentration gradient maintained by circulation/ventilation.
-Capillary network around alveoli provide large SA for gas exchange.
Men with cystic fibrosis release less sperm, and they may also require a higher energy diet than normal.
Discuss why a person with cystic fibrosis can have these symptoms. (6)
-Cystic fibrosis creates thick stickier mucus than normal.
-This causes the pancreatic duct to be blocked with mucus so digestive enzymes cant enter the intestines.
-High energy diet required as digestion is less efficient.
-Digestive enzymes trapped behind mucus damage pancreatic cells such as those that produce insulin.
-Cysts can form in pancreas.
-Sperm cant leave testes as sperm duct blocked with mucus.
-Gene mutation.
-Causing non functioning CFTR protein channel.
-Chloride ions cant move out of epithelial cells.
-Accumulation of sodium and chloride ions in cells causes water to move out of mucus via osmosis.
Explain why cystic fibrosis affects rate of oxygen uptake in lungs. (3)
-Mucus cannot be moved by cilia.
-Restricts air flow through bronchi.
-Increasing diffusion distance in alveoli.
Explain why thicker mucus is produced if functioning of CFTR channel protein is impaired. (2)
-Chloride ions cant leave through CFTR protein channel.
-Sodium ions don’t move out of cells.
-Causing water to move into cells via osmosis.
Name the prenatal test that could be used to test for Tay-Sachs disease at 11 weeks of pregnancy. (1)
-Chronic villus sampling.
Explain why a couple may choose not to have a chronic villus sampling test. (3)
-Test result may be inaccurate.
-Increase risk of miscarriage due to procedure.
-False positive may lead to termination of fetus.
-Abortion against values or beliefs of parents.
What is an inherited recessive disorder. (2)
-A recessive disorder is one caused by a faulty allele.
-Only expressed in homozygous condition.
What is an allele. (2)
-Allele is a different version of a gene.
-Found at the same locus.
Describe what happens to proteins following translation until they’re released from the cell. (3)
-Proteins are folded on the RER.
-Proteins are packaged into transport vesicles.
-Protein modified in Golgi apparatus.
-Exocytosis of protein.
Explain why enzymes that are incorrectly folded can’t carry out their function. (3)
-Tertiary structure would be different.
-Meaning active site of enzyme would not be able to bind with substrate.
-Meaning it wouldn’t be able to catalyse reaction.
Compare and contrast molecular structures of globular and fibrous proteins. (4)
-Both are chains of amino acids joined by peptide bonds.
-Both contain hydrogen bonds.
-Globular proteins have hydrophilic groups on outside whereas fibrous proteins have hydrophobic groups on outside.
-Globular have tertiary structure whereas fibrous have little to none tertiary structure.
-Globular are folded into compact shapes whereas fibrous have long chains.
How is a peptide bond formed? (2)
-Condensation reaction.
-Between amino acid and carboxyl group of adjacent amino acid.
Name an element in an R group that is not found in carbohydrates. (1)
-Nitrogen/Sulfur.
Name the products formed when several amino acids are joined together. (1)
-Polypeptide and water.
RNA produced during transcription is known as pre-mRNA.
Pre-mRNA can be modified before being translated on the ribosome.
Describe how pre-mRNA may be modified before being translated on the ribosome. (2)
-Pre-mRNA contains exons and introns.
-Introns removed and exons spliced together to produce strand of mRNA.
RNA produced during transcription is known as pre-mRNA.
Pre-mRNA can be modified before being translated on the ribosome.
Explain why modification of pre-mRNA enables one gene to give rise to more than one protein. (2)
-Exons can be spliced together in a different order.
-Therefore producing different sequence of amino acids.
