Higher Human Biology Unit 1: Human Cells Pupils Learning Outcomes

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1 Higher Human Biology Unit 1: Human Cells Pupils Learning Outcomes 1.1 Division and Differentiation in Human Cells I can state that cellular differentiation is the process by which a cell develops more specialised functions. I can state that differentiation occurs as a result of the expression of genes characteristic for that type of cell. I can state that stem cells are relatively unspecialised cells. I can state that stem cells can continue to divide and can differentiate into specialised cells of one or more types. I can state that embryonic stem cells are the unspecialised cells of the early embryo. I can state that adult (tissue) stem cells are found in locations such as the skin or bone marrow. I can state that stem cells in bone marrow can differentiate into red blood cells, platelets and the various forms of phagocytes and lymphocytes. I can state that adult (tissue) stem cells replenish differentiated cells that need to be replaced and give rise to a more limited range of cell types. I can state that all differentiated cells (except reproductive cells) derived from stem cells are known as somatic cells. I can state that somatic cells divide by mitosis to form more somatic cells. I can state that mutations that arise in somatic cells are not passed to offspring. I can state that germline cells are ones that eventually lead to the formation of sex cells (gametes). I can state that germline cells divide by mitosis to produce more germline cells or by meiosis to produce haploid gametes. I can state that mutations in germline cells are passed to offspring. I can state that stem cells can be employed therapeutically to repair damaged or diseased organs or tissues. I can state that they can also be used as model cells to study how diseases develop or for drug testing. I can state some of the ethical issues associated with the use of stem cells.

2 I can state the regulation of stem cell use includes preventing abuse and ensuring quality and safety. I can state that cancer cells can divide excessively to produce a mass of abnormal cells called a tumour. I can state that cells in a tumour do not respond to regulatory signals and may fail to attach to each other. I can state that secondary tumours can be formed as a result of cancer cells failing to attach to each other and spreading through the body. 1.2 Structure and Replication of DNA I can describe the structure of DNA with reference to the double helix, nucleotides, deoxyribose sugar, phosphates and bases. I can state that each DNA strand has a sugar phosphate backbone. I can state that the two strands of DNA are held together by hydrogen bonding between complimentary base pairs. I can state that DNA has two complimentary base pairs; Adenine & Thymine and Guanine & Cytosine. I can describe the antiparallel structure of DNA, with deoxyribose at the 3 end and phosphate at the 5 end. I can state that chromosomes are composed of tightly coiled DNA and are packaged with associated proteins. I can state that DNA replication begins with the DNA strand unwinding and unzipping to form two template strands. I can state that replication of DNA requires the enzyme DNA polymerase. I can state that DNA polymerase requires a primer to start replication. I can state that DNA polymerase can only add complimentary DNA nucleotides to the deoxyribose (3 ) end of a DNA strand. I can explain that this results in one strand being replicated continuously with the other strand being replicated in fragments. I can state that these fragments are joined together by the enzyme ligase. 1.2 Gene Expression

3 I can state that phenotype is determined by the proteins produced as a result of gene expression. I can state that only a fraction of the genes in a cell are expressed. I can state that gene expression is influenced by intra- and extra- cellular environmental factors. I can state that gene expression is controlled by the regulation of transcription and translation. I can state that RNA is single stranded. I can state that RNA contains the base uracil instead of thymine. I can state that RNA contains the sugar ribose instead of deoxyribose. I can state that messenger RNA (mrna) carries a copy of the genetic code (on DNA) from the nucleus to the ribosome. I can state that ribosomes are composed of ribosomal RNA (rrna) and proteins. I can state that transfer RNA (trna) carries a specific amino acid. I can describe the transcription of DNA into primary mrna to include the role of RNA polymerase and complimentary base pairing. I can state that the complimentary base pairs in transcription are Adenine & Uracil, Thymine & Adenine and Guanine & Cytosine. I can state that primary mrna consists of coding regions called exons and noncoding regions called introns. I can state that production of mature mrna by RNA splicing involves removal of introns and the joining together of exons. I can state that mature mrna is then transported out into the cytoplasm towards a ribosome. I can state that translation of mrna into a polypeptide by trna occurs at a ribosome. I can state that trna is folded (due to base pairing) to form a triplet anticodon site and an attachment site for a specific amino acid. I can state that and stop codons are required for the beginning and end of translation. I can describe how triplet codons on mrna and anticodons on trna translate the genetic code into a sequence of amino acids which form peptide bonds between each other.

4 I can state that as these peptide bonds are formed, a polypeptide chain is produced. I can state that trna exits the ribosome as the polypeptide chain is formed. I can state that one gene can result in the formation of a number of different proteins due to RNA splicing and post-translational modification. I can state that RNA splicing can result in the formation of different mature mrna strands depending on which primary RNA segments are treated as exons and introns. I can describe the process of post-translational protein structure modification to include cutting and combining polypeptide chains or the addition of phosphate or carbohydrate groups. 1.4 Genes and Proteins in Health and Disease I can describe the three dimensional structure of proteins to include peptide bonding, hydrogen bonding and interactions between individual amino acids. I can state that the 3D shape of a protein results from folding of the polypeptide chain. I can state that mutation can result in no protein or a faulty protein being expressed. I can state that single gene mutations involve the alteration of a DNA nucleotide sequence a result of the substitution, insertion or deletion of nucleotides. I can describe the nature of single nucleotide mutations to include missense, nonsense and splice-site mutations. I can state that nucleotide insertions or deletions result in frame-shift mutations or an expansion of a nucleotide sequence repeat. I can describe the effect of these mutations on the structure and function of the protein synthesised and the resulting effects on health. I can describe the nature of chromosomal structure mutations to include deletion, duplication and translocation. I can state that these substantial changes in chromosomes often make them lethal. Section 5: Human Genomics I can state that the sequence of bases can be determined for individual genes and entire genomes. I can state what bioinformatics is used for.

5 I can state that personalised medicine would be based on an individual s genome and could be used to identify potential risks of disease. I can state that pharmacogenetics involves the use of genome info in the development of effective drugs. I can state that Polymerase Chain Reaction (PCR) is used to amplify DNA sequences. I can explain the detailed stages involved in carrying out PCR. I can state the applications of DNA profiling. Section 6: Metabolic Pathways I can explain the difference between anabolic and catabolic pathways. I can describe how metabolic pathways are controlled. I can state that enzymes lower the activation energy required for a chemical reaction to start. I can explain the induced fit model in relation to enzyme action. I can explain the effect of substrate concentration on rate of the reaction. I can explain the effect of product concentration on the rate of reaction. I can state the three types of enzyme inhibition. I can explain the mechanisms of competitive, non-competitive and feedback (end product) inhibition. Section 7: Cellular Respiration I can describe the role of dehydrogenase in glycolysis and citric acid pathway. I can explain the role of ATP in energy transfer and phosphorylation. I can describe glycolysis. I can describe the events that occur during the citric acid cycle. I can describe the events that occur during the electron transport chain. I can state the location of the citric acid cycle and electron transfer chain. I can state the function of phosphofructokinase in respiration. I can state the role of coenzymes FAD and NAD in respiration. I can state the end products made at the end of the electron transport chain. I can state examples of substrates that can be used in respiration. I can explain how respiration is controlled. I can explain how ATP production can be inhibited. Section 8: Energy systems in muscle cells I can explain the role of creatine phosphate in energy release. I can describe the events that occur in anaerobic respiration. I can state the differences between slow twitch and fast twitch muscle fibres.