Term
| The properties of gas exchange surfaces in living organisms (large surface area to volume ratio, thickness of surface, differences in concentration) and how the strcture of the mammalian lung is adapted for rapid gas exchange. (Activities 2.3, 2.4 and 2.5) |
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Definition
| The lungs of a mammal have a large surface area, a concentration gradient is maintained and the actual gas exchange surface is very thin. Well ventilated, lots of O2. |
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Term
| The basic structure of an amino acid (structure of specific amino acid is not required). (Activity 2.6) |
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Definition
| Amino acid has an amine group attatched to a carbon attom in the centre. On the other side, it has a carboxylic acid group. the other two carbon bonds are taken up with a hydrogen atom and the residual group which makes each amino acid different. |
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Term
| The formation of polypeptides and proteins (as amino acid monomers linked by peptide bonds in condensation reactions). (Activity 2.6) |
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Definition
| Amino acids are linked by Peptide bonds. It is a condensation reaction. After the sequence of amino acids is constructed (primary structure) the secondary structure takes shape. Cirtain parts of the chain of amino acids becom an alpha-helix or beta-pleated sheets. The Tertiary structure is when the charges of the amino acids attract or repel other parts of the protein making it fold into a precise three dimensional shape. This is the final Protein, unless there are multiple chains of amino acids which make up the protein. In this case, the conjoining of multiple amino acids makes up the quaternary structure. |
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Term
| The significance of the protein's primary structure in determining its three-dimensional structure and properties (globular and fibrous proteins and types of bonds involved in three-dimensional structure). (Activity 2.6) |
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Definition
The primary structure determines secondary structure (alpha-helixes and beta-pleated sheets etc.) which determines the tertiary structure by different charges attracting and repelling each other which make up the three-dimentional structure.
Hydrogen bonds are formed to make alpha-helices and beta-pleated sheets. Hydrogen bonds, Ionic bonds or Disulphide bonds determine the final three-dimensional shape of the protein. |
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Term
| How models such as the fluid mosaic model of cell membranes are interpretations of data used to develop scientific explanations of the structure and properties of cell membranes. (Activity 2.7) |
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Definition
| what the symbols mean... ? |
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Term
| How membrane structure can be investiated practically, e.g. by the effect of alcohol concentration or temperature on membrane permeability. (Activity 2.8) |
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Definition
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Term
| The meaning of osmosis in terms of the movement of free water molecules through a partially permeable membrane (consideration of water potential is not required). (Activity 2.9) |
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Definition
| The movement of free water molecules through a partially permeable membrane. |
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Term
| Passive transport (diffusion, facilitated diffusion), active transport (including the role of ATP), endocytosis and exocytosis and the involvement of carriers and channel proteins in membrane transport. (Activity 2.9) |
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Definition
| Diffusion is the movement of molecules down a concentration gradien throught the cell membrane. Facilitated diffusion is if the molecule is too big/hydrophilic and instead goes down a concentration gradient through a channel protein which spans the cell membrane. Active transport moves molecules against the concentration gradient and requires energy in the form of ATP. Endocytosis is the movement of larger molecules into the cell by forming a vesicle around them. Exocytosis is the movement of larger molecules out of the cell by forming a vesicle around them and then releasing the contents. |
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Term
| How the expression of a gene mutatuion in people with cystic fibrosis impairs the funtioning of the gas exchange, digestive and reproductive system. |
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Definition
| Without the CFTR protein in the epithelial cells lining the gas exchange, digestive and reproductive systems the mucus becomes sticky and water cannot be added to the mucus. Because the CFTR protein cannot put Cl- ions into the mucus, the Na+ ions cannot be attracted into the mucus making water flow into the mucus. This dry and sticky mucus can block pores, or let bacteria grow in it as it is difficult to move unlike normal fluid mucus. |
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Term
| Mechanism of action and specificity of enzymes in terms of their three-dimensional structure; the understanding that enzymes are biological catalysts that reduce activation energy, catalysing a wide range of intracellular and extracellular reactions. |
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Definition
| Enzymes are proteins made up of amino acids. They have a small active site where the substrate/s fit. They biological catalysts which essentially lower the activation energy of a reaction. Intra or Extra cellular. |
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Term
| How enzyme concentrations can affect the rates of reaction and how this can be investigated practically by measuring the initial rate of reaction. (Activity 2.11) |
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Definition
| Higher conc. of enzymes will speed up the initial rate of the reaction. Using milk and an enzyme of which the products are clear... |
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Term
| The basic structure of mononucleotides (as deoxyribose or ribose linked to a phosphate and a base, i.e. thymine, uracil, cytosine and adenine or gauanine). (Activities 2.12 and 2.14) |
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Definition
| Mononucleotides (Nucleotides) are made up of a phosphate molecule, a deoxyribose sugar molecule and a base. These are joined via condensation reactions. |
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Term
| The structure of DNA and RNA (as polynucleotides composed of mononucleotides linked through condensation reactions). (Activities 2.12 and 2.14) |
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Definition
| DNA is made up of many nucleotides --> polynucleotides. Each nucleotide has a corresponing base pair and nucleotide which runs in the opposite direction. The nucleotides are joined by hydrogen bonds between the bases. The polynucleotides form a double helix shape. Bonds between the nucleotides are formed through condensation reactions. |
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Term
| How complementary base pairing and the hydrogen bonding between two complementay strands are invlolved in the formation of the DNA double helix. (Activities 2.12 and 2.14) |
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Definition
| If the base is Adenine (A) then the corresponding base will be Thymine (T) and vice versa. If the base is Guanine (G) then the corresponding base will be Cytosine (C) and vice versa. This is because of the hydrogen bonds between the base pairs. Because of the hydrogen bonds between the bases, the structure of DNA is a double helix. |
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Term
| The nature of the genetic code (triplet code only) and a gene is a sequence of bases on a DNA molecule coding for a sequece of amino acids in a polypeptide chain. (activity 2.14) |
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Definition
| The genetic code is made up of the base pairs in DNA. Every three bases codes for a different amino acid. Thus determining the primary structure of a protein. |
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Term
| Outline of protein synthesis, including the role of transcription, translation, messendger RNA and the template (antisense) DNA strand (details of the mechanism of protein synthesis on ribosomes are not required.) (Activity 2.14) |
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Definition
Transcription is the first process and is carried out in the nucleus of a cell. The sense strand (one side of the DNA) and the antisense strand (the other side of the DNA) are "unzipped" or the hydrogen bonds are boken. Then the messenger RNA is created from free base pairs in the nucleus this is copied from the antisense strand thus giving it the same base pairs as the sense strand (except for Thymine which is replaced with Uracil). This is the end of Transcription.
The second stage in protein synthesis is Translation and happens in the cytoplasm of the cell. The mRNA leaves the nucleus through a pore and enters the cytoplasm. Here, the protein is synthesised in a ribosome. Inside the ribosomes are transfer RNA. tRNA has on it an anitcodon which will match up with every three base pairs on the mRNA and the amino acids on the end of the tRNA will form peptide bonds with each other forming the primary structure of a protein. |
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Term
| The process of DNA replication (including the role of DNA polymerase). (Activity 2.15) |
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Definition
| Hydrogen bonds between bases break and the DNA "unzips" fully. The corresponing base pairs pair up with the bases and and DNA polymerase joins the nucleotides together forming two daughter strands. |
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Term
| How Meselson and Stahl's classic experiment provided new data that supported the accepted theory of replication and refuted competing theories. (Acitivity 2.15) |
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Definition
DNA replication is semi-conservative. How do we prove this?
Other than semi-conservative it could be Fragmentary replication - just a mixture of new and old strands, or it could be conservative replication - the mother has the original and the daughter has two complete new strands.
The two scientists grew DNA with only 15N, making it heavy and some made only with 14N making it light. The DNA has now been "labelled". The heavy type of DNA was put in a test tube with light nucleotides and allowed to replicate once. Then it was centrifuged. The results showed that there was just one stripe of DNA in the test tube. This meant that the DNA can only replicate via the semi-conservative or fragmentary replication. The DNA was allowed to replicate again, and then it was centrifuged. After this two stripes of DNA were visible, one medium weight and the other light. This supports the semi-conservative model only. |
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Term
| How errors in DNA replication can give rise to mutations and how cystic fibrosis results from one of a number of possible gene mutations. |
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Definition
| If a single base is missed out at some point, the amino acids will all be affected as each codon is out of sync by one. The same would be the case if one was accidentally added. Sometimes the base could just be read wrong so only one amino acid would be wrong but this could still change the shape of the protein in a negative way. In CF the main mutation is at ATP binding site 1. Where three nucleotides are deleted losing an amino acid and resulting in missfolding of the CFTR protein. |
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Term
| The meanings of the terms: gene, allele, genotype, phenotype, recessive, dominant, homozygote, and heterozygote. (Activity 2.16) |
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Definition
Gene- a length of DNA which codes for a protien.
Allele- alternative forms of the same gene.
Genotype- made up of the alleles a person has.
Phenotype- the observable effect caused by the genotype.
Recessive- only affects the gene if the other allele is also recessive.
Dominant- affects the gene even if there is a recessive allele present.
Homozygote- both alleles are either dominant or recessive.
Heterozygote- both alleles are different. |
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Term
| Monohybrid inheritance, including the interpretation of genetic pedigree diagrams. (Activity 2.16) |
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Definition
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Term
| The principles of gene therapy and the distinction between somatic and germ line therapy. (Activity 2.18) |
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Definition
| Gene therapy is essentially changing the alleles of a gene so that it will make the CFTR protien using a genetically modified virus. However if this is somatic (body) therapy, then only those cells are going to be influenced and once they die, the new cells will again have the faulty CFTR protien. They way to solve this problem is to do the same thing except with germ (sperm or egg) cells. This would mean that all the cells in the body would be produced in the right way with the right protien. However this is presently illegal as there are ethical objections. |
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Term
| The uses of genetic screening: identification of carriers, pre-implantation genetic diagnosis and prenatal testing (amniocentesis and choronic villus sampling) and discuss the implications of prenatal genetic screening. (Activity 2.19) |
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Definition
| Genetic screening can be used to find out if the person carries the allele for CF or not. Pre-implantation genetic diagnosis tests the embryo before being put in the mother's womb. Prenatal testing is used before a baby is born. Amniocentesis includes putting a needle into amniotic fluid to collect cells which have fallen of the placenta and foetus. slight risk of miscarriage. Chronic Villus Sampling involves taking a small piece of placental tissue and analysing genes from that but has a higher chance of a miscarriage. |
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Term
| Identify and discuss the social and ethical issues related to genetic screening from a range of ethical viewpoints. (Activity 2.19) |
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Definition
| Could cause a miscarriage. May make mother want an abortion. The Baby cannot decide if it wants the treatment or not.... |
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