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135 Cards in this Set
- Front
- Back
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Explain missense |
Replacing one amino acid codon with another. |
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Explain nonsense. |
Replacing an amino acid codon with a premature stop codon - no amino acid is made and the process stops. |
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Explain splice site mutations. |
Creating or destroying the codons for exon/intron splicing. |
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How are different mRNA molecules produced from the same primary transcript? |
Different mRNA molecules are produced from the same primary transcript depending on which RNA segments are treated as exons or introns. |
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How is the polypeptide finally formed in translation? |
Codon recognition of incoming tRNA, peptide bond formation and exit of tRNA from the ribosome as polypeptide is formed. |
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What does tRNA do? |
Each tRNA carries a specific amino acid. |
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Explain transcription. |
RNA polymerase moves along DNA, unwinding and unzipping the double helix and synthesising a primary transcript of RNA by complementary base pairing. |
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What does tRNA fold to form in translation? |
tRNA folds due to base pairing to form a triplet anticodon site and attatchment site for a specific amino acid. |
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Describe how DNA polymerase replicates DNA. |
DNA polymerase can only add complementary DNA nucleotides to the deoxyribose (3') end of a DNA strand. This results in one strand being replicated continuously and the other strand replicated in fragments which are joined together by ligase. |
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What happens to the nucleus during cell divison? |
During cell division the nucleus of a somatic cell divides by mitosis to maintain the diploid chromosome number. Diploid cells have 23 pairs of homologous chomosomes. |
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Are mutations in germline cells passed onto offspring? |
They are. |
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What does it mean that the cells of an early embryo are pluripotent? |
The inner mass cells of an early embryo (blastocyst stage) are pluripotent as they can make nearly all of the cell types in the body. |
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What does mRNA do? |
mRNA carries a copy of the DNA code from the nucleus to the ribosome. |
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What does rRNA do? |
rRNA and proteins form the ribosomes. |
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How many genes in a cell are expressed? |
Only a fraction. |
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How is a secondary cancerous tumour formed? |
The cancer cells do not respond to regulatory signals and may fail to attaych to eachother. If they fail to attatch to each other they can spread through the body to form secondary tumours. |
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Descirbe the basic structure of DNA. |
Nucleotides consist of deoxyribose sugar, phosphate and a base. DNA has a sugar-phosphate backbone. |
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Explain complementary base pairing. |
Adenine with thymine and guanine with cytosine. |
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How is a cancerous tumour formed? |
Cancer cells divide excessively to produce a mass of abnormal cells, called a tumour. |
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What two things have to be considered about stem cells? |
The ethical issues and the regulation of their use. |
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When germline cells divide what do they produce? |
Germline cells divide by mitosis to produce more germline cells or by meiosis to produce haploid gametes. |
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What links to form polypeptides? |
Amino acids are linked by peptide bonds to form polypeptides. |
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What do the sunstantial changes in chromosome mutations make them? |
They often make them lethal. |
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How do somatic cells form? |
Somatic cells divide by mitosis to form more somatic cells. |
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What should the therapeutic uses of stem cells be exemplified by reference to? |
By reference to the repair of diseased or damaged organs, e.g. corneal transplants and skin grafts for burn victims. |
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What are the main body tissue types and what do these tissues form? |
The main body tissue types are: epithelial; connective; muscle and nerve tissue. The body organs are formed from a variety of these tissues. |
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What do the main body tissue types do/consist of? |
Epithelial cells cover the body surface and line body cavities. Connective tissue includes blood, bone and cartilage cells. Muscle cells form muscle tissue. Nerve cells form nervous tissue. |
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Give an example of a mulitpotent tissue (adult) stem cell. |
For example, blood (haematopoietic) stem cells can make all of the cell types in the blood. |
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What does it mean that tissue (adult) stem cells are multipotent? |
Tissue stem cells are multipotent as they can make all of the cell types found in a particular tissue type. |
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What are the two types of stem cells? |
Stem cells - embryonic and tissue (adult) stem cells. |
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What is DNA the molecule of and can it direct its own replication? |
DNA is the molecule of inheritance and it can direct its own replication. |
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Describe PCR |
DNA is heated to seperate the strands and then cooled fpr primer binding. Heat-tolerant DNA polymerase then replicates the region of DNA. Releated cycles of heating and cooling amplify this region of DNA. |
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What does cooling allow for in PCR? |
Cooling allows primers to bind to target sequences. |
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How can a diagnosis or risk of disease onset be made? |
By screening a cell sample from a patient for the presence or absence of a particular sequence, a diagnosis of disease status or risk of disease o set can be made. |
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How is the genetic code translated into a sequence of amino acids? |
Triplet codons on mRNA and anticodons translate the genetic sequence of amino acids. Start and stop codons exist. |
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What do tissue (adult) stem cells in bone marrow develop into? |
Development of tissue (adult) stem cells in bone marrow into red blood cells, platelets and the various forms of phagocytes and lymphocytes. |
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Where do cells store their genetic information? |
All cells store their genetic information in the base sequence of DNA. |
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What is DNA replicated by? And where? |
Prior to cell division, DNA os replicated by a DNA polymerase. This process occurs at several locations on a DNA molecule. |
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How is protein structure modified post-translation? |
Post-translation protein structure modification by cutting and combining polypeptide chains or by adding phosphate or carbohydrate groups to the protein. |
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Describe the structure of RNA. |
RNA IS single stranded, contains uracil instead of thymine and ribose sugar instead of deoxyribose sugar. |
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What are other uses of stem cells? |
Stem cells can also be used as model cells to study how diseases develop or for drug testing. |
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What do mutations result in? |
Mutations result in no protein or a faulty protein being expressed. |
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What are genetic disorders caused by? |
Geetic disorders are caused by changes to genes or chromosomes that result in the proteins not being expressed or the proteins expressed not functioning correctly. |
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What do single gene mutations involve? |
Single gene mutations involve the alteration of a DNA nucleotide sequence as a result of the substitution, insterion or deletion. |
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What do single gene mutations have an effect on? |
On the structure and function of the protein synthesised and the resulting effects on health. |
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What can computer programes be used to identify? |
Computer programs can be used to identify gene sequences by looking for coding sequences similar to known genes, start sequences or sequences lacking stop codons. They can also used to identify base sequences that correspond to the amink acid sequence of a protein. |
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What do applications of DNA profiling allow? |
Allow the identification of individuals through comparison of regions of the genome with highly variable numbers of repetitive sequences of DNA. |
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Decribe deletion. |
Loss of a segment of a chromosome. |
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Describe duplication. |
The repeat of a segment of a chromosome. |
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Describe translocation mutations. |
The rearrangement of chromosomal material involving two or more chromosomes. |
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What are the possible natures of single-nucleotide substitutions? |
Missense, nonsense and splice site mutations. |
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What are introns and exons? |
Genes have introns (non-coding regions of genes) and exons (coding regions of genes). |
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What are bioinformatics? |
The use of computer technology to identify DNA sequences. The sequence of DNA bases can be determined for individual genes and entire genomes. |
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What are cells of the early embryo called in the lab? |
Embryonic stem cells. |
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What does stem cell research provide information on? |
Cell growth, differentiation and gene regulation work. |
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What is PCR? |
The polymerase chain reaction is a technique for the amplication of DNA. |
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What is systematics? |
Systematics compares human genome sequence data and genomes of other species to provide information on evolutionary relationships and origins. |
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How can the data produced by DNA and protein sequencing be managed and analysed. |
The enormous amount of data produced by DNA and protein sequencing can be managed and analysed using computer technology and shared over the internet. |
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What do chromosomes consist of? |
Chromosomes consist of tightly coiled DNA and are packaged with associated proteins. |
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What are primers complementary to in PCR? |
They are complementary to specific target sequences at the two ends of the region to be amplified. |
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How is DNA prepped for replication? |
DNA is unwound and unzipped to form two template strands. DNA polymerase needs a primer to start replication. |
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Where is DNA transribed? |
Transcription of DNA into primary and mature RNA transcript in the nucleus. |
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What is phenotype determined by? |
Phenotype is determined by the proteins produced as a result of gene expression. |
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What are stem cells? |
Stem cells are unspecialised somatic cells that can divide to make copies of themselves (self-renew) and/or differentiate into specialised cells. |
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How are the two DNA strands held together? |
The two DNA strands are held together by weak hydrogen bonds and have an antiparallel structure, with deoxyribose at 3' and phosphate at 5' ends of each strand respectively. |
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When can the inner mass cells of an early embryo self-renew? |
Under the right conditions, in the lab. |
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How are proteins held in a 3D shape? |
Peptide bonds, hydrogen bonds and interactions between individual amino acids. |
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How can different proteins be expressed from one gene? |
Different proteins can be expressed from one gene as a result of alternative RNA splicing and post translational modification. |
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How do proteins have a wide range of functions? |
Proteins have a large variety of structures and shapes resulting in a wide range of functions. |
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What do nucleotide instertions or deletions result in? |
Nucleotide insertions or deletions result in frame-shift mutations or an expansion of a nucleotide sequence repeat. |
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What does PCR use to amplify DNA? |
It uses complemetary primers for specific target sequences. |
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What is gene expression influenced and controlled by? |
Gene expression is influenced by intra and extra cellular enviromental factors. It is alo controlled by the regulation of both transcription and translation. |
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What is the genotype determined by? |
The genotype is determined by the sequence of DNA bases. |
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What kind of steps and routes do metabolic pathways have? |
They have reversible steps and alternative routes. Metabolic pathways may exist that can bypass steps in a pathway. |
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What is metabolism? |
Metabolism encompasses the integrated and controlled pathways of enzyme catalysed reactions within a cell. |
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What is the difference between anabolic and catabolic pathways? |
Anabolic pathways require energy and involve biosynthetic processes. Catabolic pathways release energy and involve the breakdown of molecules. |
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Describe the gene expression and presence of enzymes in the cells. |
Genes for some enzymes are continuously expressed. These enzymes are always present in the cell and their control involves the regulation of their rate of reaction. |
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Describe the reversal and direction of metabolic reactions. |
Most metabolic reactions are reversible and the presence of a substrate or the removal of a product will drive a sequence of reactions in a particular direction. |
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Name the three main components of enzyme-substrate binding. |
Induced fit, the active site of enzymes and activation energy. |
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What is the role of the active site? |
The role of the active site in orientating reactants, lowering the activation energy with the transition state and the release of products with low affinity for the active site. |
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What effect does the substrate and end product concentration have? |
The effects of substate and end product concentration on the direction and rate of enzymes reactions. |
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How are metabolic pathways controlled through inhibition? |
Control of metabolic pathways through competitive (binds to active site), non-competitive (changes the shape of active site) and feedback inhibition (end product binds to an enzyme that catalyses a reaction early in the pathway). |
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How can competitve inhibition be reversed? |
Increasing the substrate concentration. |
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What is the very basic sentence that describes cellular respiration? |
Glucose is broken down, hydrogen ions and electrons are removed by dehydrogenase enzymes, releasing ATP. |
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What is the connection between cellular respiration and metabolism? |
The metabolic pathways of cellular respiration are central to metabolsim. They yield energy and are connected to many other pathways. |
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What is ATP for? |
ATP is used to transfer energy to synthetic pathways and other cellular processes where energy is required. |
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What, in a sentence, happens in the first stage of respiration? |
The breakdown of glucose to pyruvate in the cyroplasm in glycolysis, and the progression pathways in the presence or absence of oxygen. |
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What happens in glycolysis, in detail. |
The phosphorylation of intermediates in glycolysis in an energy investment phase and the direct generation of ATP in an energy pay-off stage. |
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Describe the role of phosphofructokinase in glycolysis. |
The first phosphorylation leads to a product that can continue to a number of pathways and the second phosphorylation, catalysed by phosphofructokinase, is an irreversable reaction leading only to the glycolytic pathway. Pyruvate progresses to the citric acid cycle if oxygen is avaliable. |
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How is pyruvate prepared for the citric acid cycle? |
Pyruvate is broken down into an acetyl group that combines with coenzyme A to be transferred to the citric acid cycle as acetyl coenzyme A. |
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How is citrate formed in the citric acid cycle? |
Acetyl (coenzyme A) combines with oxaloacetate to form citrate followed by the enzyme mediated steps of the cycle. |
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What is produced in the citric acid cycle? |
This cycle results in the generation of ATP, the release of carbon dioxide and the regeneration of oxaloacetate in the matrix of the mitochondria. |
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How do NAD and FAD become NADH and FADH2? |
Dehydrogenase enzymes remove hydrogen ions and electrons which are passed to the coenzymes NAD or FAD to form NADH or FADH2 in glycolysis and citric acid cycle. |
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What is the electron transport chain? |
It is a collection of proteins attatched to a membrane. |
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Describe the electron transport chain. |
NADH and FADH2 release high energy elecrons to the electron transport chain where they pass along the chain, releasing energy. The energy is used to pump H ions across the the inner mitochondrial membrane. The return flow of H ions drives ATP synthase and produces the bulk of ATP generated by cellular respiration. |
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Describe how exactly ATP is synthesised in the electron transport chain. |
High energy electrons are used to pump hydrogen ions across a membrane and the return flow of these ions rotates part of the membrane protein ATP synthase, catalysing the synthesis of ATP. |
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What is the final electron acceptor? |
Oxygen is the final electron acceptor, which combines with hydrogen ions and electrons to form water. |
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What are the substrates for respiration? |
The role of starch, glycogen, other sugar molecules, amino acids and fats in the respiratory pathway. |
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How are starch and glycogen respiratory substrates? |
Starch and glycogen are broken down to glucose for use as a respiratory substrate. |
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How are other sugar molecules substrates for respiration? |
Other sugar molecules can be converted to glucose or glycolysis intermediates for use as respiratory substrates. |
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How are fats and substrates for respiration? |
Proteins and fats can be broken down to amino acids and converted to intermediates of glycolysis and the citric acid cycle for use as respiratory substrates. |
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How does the cell conserve its resources? |
By only producing ATP when required. |
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When do ATP supplies increase and decrease? |
ATP supply increases with increasing rates of glycolysis and the citric acid cycle, and decreases when these pathways slow down. |
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What happens when the cell produces more ATP than it needs? |
If the cell produces more ATP than it needs, the ATP inhibits the action of phosphofructokinase slowing the rate of glycolysis. |
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How are the rates of glycolysis and the citric acid cycle synchronised? |
The rates of glycolysis and the citric acid cycle are synchronised by the inhibition of phosphofructokinase by citrate. |
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What happens if citrate accumulates or its consumption increases? |
If citrate accumulates, glycolysis slows down and when citrate consumption increases glycolysis increases the supply of acetyl groups to the citric acid cycle. |
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What does the cell do during strenuous muscle activity? |
The cell rapidly breaks down its reserves of ATP to release energy. |
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How do muscle cells replenish ATP pools during rigorous bouts of exercise? |
Muscle cells have an additional source of energy in creatine phosphate that can be used to replenish ATP pools during rigorous bouts of exercise. |
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What is creatine phosphate? |
Creatine phosphate breaks down to release energy and phosphate that is used to convert ADP to ATP at a fast rate. |
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How long does the creatine system last? |
This system can only support strenuous muscle activity for around 10 seconds, when the creatine phosphate supply runs out. When muscle energy demand is low, ATP from cellular respiration is used to restore the levels of creatine phosphate. |
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What happens to the muscle cells during vigorous exercise? |
During vigorous exercise, the muscle cells do not get sufficient oxygen to support the electron transport chain. Under these conditions, pyruvate is converted to lactic acid. |
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How is pyruvate converted to lactic acid during vigorous exercise? |
This conversion involves the transfer of hydrogen from the NADH produced during glycolysis to pyruvic acid to produce lactic acid. |
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What does the production of lactic acid do during vigorous exercise? |
This regenerates the NAD needed to maintain ATP production through glycolysis. Lactic acid accumulates in muscle causing fatigue. |
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What happens when the oxygen debt is repaid when exercise is complete? |
Oxygen debt is repaid when exercise is complete allows respiration to provide the energy to convert lactic acid back to pyruvic acid and glucose in the liver. |
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What are slow-twitch muscle fibres good for? |
Slow-twitch muscle fibres are good for endurance activities like long distance running, cycling or cross-country skiing |
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Describe the muscle tissue composition in humans. |
Most human muscle tissue contains a mixture of both slow and fast twitch muscle fibres. Athletes show distinct patterns of muscle fibres that reflect their sporting activities. |
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How do slow twitch muscle fibres generates ATP and what do they consist of? And what is their major storage fuel? |
Slow twitch muscle fibres rely on aerobic respiration to generate ATP and have many mitochondria, a large blood supply and a high concentration of the oxygen storing protein myoglobin. The major storage fuel of slow twitch muscle fibres is fats. |
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Describe the contractions of slow twitch muscle fibres. |
Slow twitch (type 1) muscle fibres contract more slowly, but can sustain contractions for longer and so are good for endurance activities. |
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What are fast twitch muscle fibres good for? |
Fast twitch muscle fibres are good for activities like sprinting or weightlifting. |
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How do fast twitch muscle fibres generate ATP, what do they consist of and what is their major storage fuel? |
Fast twitch muscle fibres can generate ATP through glycolysis only and have few mitochondria and a lower blood supply than slow twitch muscle fibres. The major storage fuels of fast twitch muscle fibres are glycogen and creatine phosphate. |
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Describe the contractions of fast twitch muscle fibres. |
Fast twitch (type 2) muscle fibres contract more quickly, over short periods, so are good for burst of activity. |
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How are metabolic pathways controlled? And regulated? |
Metabolic pathways are controlled by the presence or absence of particular enzymes in the metabolic pathway and through the regulation of the rate of reaction of key enzymes within the pathway. Regulation can be controlled by intra and extracellular signal molecules. |
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What can the cells of the early embryo make? |
The cells of the early embryo can make all of the differentiated cell types of the body. They are pluripotent. |
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What is cellular differentiation? |
Cellular differentiation is the process by which a cell develops more specialised functions by expressing the genes characteristic for that type of cells. |
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What are the types of chromosome structure mutations? |
Deletion, duplication and translocation. The structure of a chromosome can be altered. |
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What are tissue (adult) stem cells involved in? |
They are involved in the growth, repair and renewal of the cells found in that tissue. They are multipotent. |
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What does a differentiated cell express? |
Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell. |
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What is RNA splicing? |
The introns of the primary transcript of mRNA are non-coding and are removed in RNA splicing. The exons are coding regions and are joined together to form mature transcript. This process is called RNA splicing. |
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What is it important to distinguish between in mutations, and realise about diseases? |
The importance of distinguishing between neutral and harmful mutations and the complex nature of many diseases. |
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What is personalised medicine? |
Personalised medicine is based on an individual's genome. Analysis of an individual's genome may lead to personalised medicine through understanding the genetic component of risk of disease. |
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Where does translation occur? |
Translation of mRNA into a polypeptide by tRNA at the ribosome. |
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How is the 3D shape of the protein formed? |
Polypeptide chains fold to form the three dimensional shape of the protein. |
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What is important in the choice of effective drugs? |
Pharmacogenetics and the use of genome information in the choice of effective drugs. |
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What are DNA probes for? |
Arrays of DNA probes are used to detect the presence of specific sequences in samples of DNA. |
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What are probes? |
The probes are short single stranded fragments of DNA that are complementary to a specific sequence. Fluorescent labelling allows detection. |
