Inheritance, Variation & Evolution

• DNA has a double helix structure. How many strands is the helix made up of?

  Two
• The DNA in typical human cell is found in tight coils known as chromosomes.
• Chromosomes exist in pairs. The chromosomes in the 23rd pair are known as the?

  Sex chromosomes
• Women have XX chromosomes

  Men have XY chromosomes
• What's a gene?

  A small section of DNA that codes for a specific protein
• DNA can code for proteins by coding for the sequence in which amino acids are joined together. 
• What's a genome?

  The entire set of genetic material in an organism 
•  Understanding the genomes of different people around the world can tell us about the migration patterns of our ancestors.
• Where are the chromosomes found in the cell?

  Nucleus
• Alleles are the different versions of a particular gene.
• Humans have two copies of each gene (alleles). If both alleles are the same, the person is said to be Homozygous for that gene.
• Alleles can be either dominant or recessive.
• In order to be expressed, how many recessive alleles must be present?

  Two
• What is a phenotype?

  The characteristics an organism has as a result of their genotype
• What's another definition for genotype?

  the two alleles present for a particular gene'. 
• If the alleles are different, the person is said to be Heterozygous for that gene.
• Which process is used to create gametes?

  Meiosis 
• Do animals usually reproduce via sexual or asexual reproduction?

  Sexual reproduction
• Sexual reproduction involves the combination of DNA from two different parents. This means that the offspring will be genetically different to either of their parents. 
• What do we call the fusion of male of female gametes? 

  Fertilisation
• During sexual reproduction in plants, which two gametes fuse together?

  Pollen and egg
• Sperm and egg cells are haploid cells and only have 23 chromosomes. When a sperm fertilises the egg though, they form a diploid cell that has 46 chromosomes.
• As a result of asexual reproduction, the offspring are genetically identical 
• When fungi and plants reproduce asexually, which process do they use?

  Mitosis
• When bacteria reproduce asexually, which process do they use?

  Binary fission
• What are examples of sex cells (gametes)?

  Sperm and egg
• What does the term 'haploid' mean?

  A cell that only has half the normal amount of genetic material
• During the process of meiosis, how many times does the cell divide?

  Two
• When two haploid cells join, they form a diploid cell. 
• As a result of meiosis, how many cells are produced?

  Four
• How would you describe the genotype 'AA'?

  Homozygous dominant 
• How would you describe the genotype 'Hh?

  Heterozygous
• Are the cells produced by meiosis genetically identical to each other, or genetically unique?

  Genetically unique 
• How would you describe the genotype 'dd'?

  Homozygous recessive 
• Is cystic fibrosis a dominant or recessive condition?

  Recessive 
• Which genotype would involve being a carrier for cystic fibrosis

  Hetrozygous
• What is polydactyly? 

  A condition in which an individual can be born with extra fingers or toes 
• Polydactyly is an example of an 'inherited disease', what does this mean? 

  It can be inherited from an individual's parents
• Is polydactyly caused by a dominant or a recessive allele? 

  Dominant 
• Which part of a human body cell is affected by cystic fibrosis?

  Cell membrane