Flashcards
Topic 6: Variation and Inheritance
Flashcards do conjunto (34)
- 1Define: 1. Gene 2. DNA 3. Chromosome 4. Genome1. A code for a specific protein
2. A collection of genes in a double helix structure. It determines characteristics of living things
3. A very long molecule of DNA
4. Every single gene that makes up an organism - 2How does DNA code for a protein?1. Genes consist of four bases - A, T, C and G
2. The bases pair with each other - A to T and C to G
3. One side of the DNA is copied onto messenger RNA (mRNA)
4. The mRNA leaves the nucleus and travels to a ribosome
5. The ribosome reads the mRNA 3 bases at a time
6. Each set of 3 bases corresponds to an amino acid or other instructions (non-coding DNA)
7. Carrier molecules bring the amino acids to the ribosome to assemble the protein - 3What is DNA made of?Nucleotides - a deoxyribose sugar with a phosphate and a base
- 4What is a mutation?A change to the genetic code
- 5How can mutations occur?Usually spontaneous but exposure to radiation can increase the likelihood of one
- 6What could be problems with a protein that has been altered by a mutation?1. If an enzyme's active site changes, the substrate may not be able to bind to it
2. Structural proteins could lose their strength - 7What are the types of mutationInsertion - A new base is inserted into the sequence
Deletion - A random base is removed from the sequence
Substitution - A random base is changed to another - 8What is asexual reproduction?Reproduction that produces genetically identical cells
- 9Give examples of animals that reproduce asexuallyBacteria
Strawberry plants
Some types of snakes (females can fertilise their own eggs) - 10What type(s) of cell division will result in asexual reproduction?Mitosis
Binary Fission - 11What are the advantages of asexual reproduction?One parent
Uses less energy - organisms don't have to find a mate
Faster than sexual reproduction
Many offspring can be produced in favourable conditions - 12What is sexual reproduction?Reproduction that produces genetically identical cells
- 13Give examples of organisms that reproduce sexuallyMost animals and plants e.g. humans and daffodils
- 14How does sexual reproduction occur?Fusion of sex cells (gametes)
- 15What type of cell division results in the formation of gametes?Meiosis
- 16Explain meiosisBefore division: genetic information duplicated, crossing over (homologous chromosomes exchange genetic info)
First division: Chromosomes line up along equator and pulled apart. Mixture of maternal and paternal chromosomes go into each cell
Second division: Chromosomes line up and are pulled apart again leaving four gametes with half the number of chromosomes. - 17What are the advantages of sexual reproduction?Genetic variation in offspring
More chance of some of the offspring surviving
Natural selection occurs
Possible to speed up natural selection using selective breeding - 18Name some species can reproduce both sexually and asexuallyMalaria - The protest that causes malaria reproduces sexually in the mosquito and asexually in the human host
Fungi - many species produce spores both sexually and asexually
Plants - Many produce seeds sexually and also reproduce asexually e.g. strawberry plants generate runners - 19Which chromosomes determine sex?X and Y chromosomes
- 20What are the combinations for each?XX - Female
XY - Male - 21How can you show possible genetic combinations?Using a genetic diagram
- 22What is a variation of a gene called?An allele
- 23What is the difference between dominant and recessive alleles?Dominant - always takes priority
Recessive - Will only take priority if there are no dominant alleles - 24How are dominant and recessive alleles represented in genetic diagrams?Dominant - Capital letter
Recessive - Lowercase letter - 25Define: Homozygous dominant Homozygous recessive Heterozygous Genotype PhenotypeHomozygous dominant = two dominant alleles
Homozygous recessive = two recessive alleles
Heterozygous = One dominant and one recessive allele
Genotype = The combination of alleles
Phenotype = The characteristic the gene controls - 26What is cystic fibrosis?Recessive disorder
Lots of thick, sticky mucus in lungs and pancreas
Both parents must have the allele to pass the disorder onto their offspring - 27What is a carrier?A person with one recessive allele
- 28What is polydactyly?Dominant disorder
Causes development of extra fingers or toes
Dominant gene so will automatically control the phenotype if present - only one parent needs the allele - 29How are embryos screened for genetic disorders?Following IVF a cell is removed from a developing embryo and its genetic material is analysed
- 30Arguments for embryo screeningHelps to stop people suffering
Expensive to treat people with disorders
Laws to stop it going too far (sex cannot be chosen in the UK unless it's for medical reasons) - 31Arguments against embryo screeningImplies that people with genetic problems are undesirable - could increase prejudice
May come a point when everyone wants to choose embryos to pick the most desirable one
Screening is expensive - 32Describe natural selectionSome animals are better adapted to surroundings than others
These animals are more likely to survive and reproduce
Genes can be passed onto offspring - 33Who created the theory of evolution?Charles Darwin
- 34—
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- Year 10 Biology (Topic 6: Variation and Inheritance) FlashCards sobre Topic 6: Variation and Inheritance, criado por James Norman em 27-04-2018.
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- James Norman
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