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23 Cards in this Set
- Front
- Back
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A gene codes for polypeptides, including enzymes Define: Genetic code |
The sequence of base triplets (codons) in mRNA which codes for specific amino acids |
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Describe: Nucleotide structure Name: 4 bases |
(A) - Adenine (T) - Thymine (C) - Cytosine (G) - Guanine |
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How a nucleotide sequence codes for the amino acid sequence in a protein: |
- Order of bases in a gene determines order of amino acids - Each amino acid is coded by a sequence of 3 bases (triplet or codon) - Different proteins have different number and order of amino acids |
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Role of mRNA in construction of a polypeptide |
Carries genetic code from DNA in the nucleus to the cytoplasm, where its used to make a protein during translation |
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Role of tRNA in construction of a polypeptide |
It carries the amino acids that are used to make proteins to the ribosomes |
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Mutations cause changes to the sequence of nucleotides in DNA molecules Some mutations can have different effects: Beneficial, neutral or harmful on the way a protein functions - mutations occur by: |
- Substitution -Deletion -Insertion -Duplication -Inversion |
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Mutations that don't affect an organism - neutral effect |
1. Changes in a base triplet that code for an AA may not effect AA because some AA are coded for by more than one triplet 2. Triplet produces an AA which is chemically similar so functions like the original AA 3. Mutated triplet codes for an AA not involved with the proteins function |
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Mutations with beneficial effects and harmful effects |
- Can have an advantageous effect on the organism - increasing its chance of survival - ^Same as above but reversed (less chance of survival) |
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Cyclic AMP function: |
cyclic AMP activates proteins by altering their three-dimensional structure -can make enzymes active or inactive by altering active site |
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Explain genetic control of protein production in a prokaryote using the lac operon |
-An operon is a section of DNA that contains structural genes, control elements and regulatory gene -r gene codes for transcription factor (tf) -this binds to DNA and switches genes on/off -shape can be alter by binding of some molecules meaning the amount of molecules in an environment can control the synthesis of some proteins by affecting tf binding |
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About: Homeotic genes Define: Body plan |
-Genes that code for proteins that control body plan development -Have regions called homeobox sequences -these code for part of the protein called the homeodomain Body Plan: the general structure of an organism |
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How homeotic genes control development |
-Homeodomain binds to specific sites on DNA -Enables protein to work as a transcription factors -proteins bind to DNA at the start of developmental genes activating or repressing transcription -so altering production of proteins involved in the development of the body plan |
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Define: Apoptosis |
Programmed cell death. An orderly process where by cells die after they have undergone the maximum number of divisions. |
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How Apoptosis can act as a mechanism to change body plans |
-bulk of structures created by mitosis and differentiation and then apoptosis refines the parts by removing unwanted structures -All cells have genes which code for proteins that promote or inhibit apoptosis -During development some of these genes are switched on and off in selected cells so the correct body plan develops |
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1. What is meiosis? 2. Stages of meiosis |
1. A type of cell division that occurs in reproductive organs to produce gametes
2. Before: Interphase Then: Meiosis I - prophase 1, metaphase 1, anaphase 1, telophase 1 Finally: Meiosis II |
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DEFINITIONS 1. DNA 2. Histones |
1. Deoxyribonucleic acid - a polymer of nucleotide molecules 2. Type of protein associated with DNA in eukaryotes. DNA is wound around these proteins to form chromatin |
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DEFINITIONS 3. Chromatin 4. Chromosome |
3. Chromosomes are made of this material. It consists of DNA and histone proteins 4. A length of DNA wrapped around histone proteins. There are 46 in the nuclei of human body cells. |
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DEFINITIONS 5. Chromatid 6. Supercoiled chromosome |
5. A replicated chromosome appears as two identical strands. Each strand is called a chromatid. The two strands are known as sister chromatids. 6. A chromosome where the chromatin has coiled up to make a chromosome shorter and wider. these chromosomes are now visible with a light microscope. |
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DEFINITIONS 7. Allele 8. Locus 9. Phenotype |
7. An alternative version of a gene 8. Specific position on a chromosome, occupied by a specific gene 9. Observable characteristics of an organism |
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DEFINITIONS 10. Genotype 11. Dominant |
10. Alleles present within cells of an individual, for particular trait/characteristic 11. Characteristic in which the allele responsible is expressed in the phenotype even in those with heterozygous genotypes |
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DEFINITIONS 12. Codominant 13. Recessive |
12. A characteristic where both alleles contribute to the phenotype 13. Characteristic in which the allele responsible is only expressed in the phenotype if there is no dominant allele present |
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DEFINITIONS 14. Linkage 15. Crossing over |
14. Genes for different characteristics that are present at different loci on the same chromosome are linked 15. Where non-sister chromatids exchange alleles during prophase1 of meiosis |
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Explain how meiosis and fertilization can lead to variation through the independent assortment of alleles |
-Meiosis 1: different combo of maternal & paternal chromosomes go into each cell -each has different combo of alleles -Meiosis 2: different combo of chromatids go into each daughter cell |
