science revision BIOLIGY

• what are gametes?


  Sex cells or reproductive cells.
• meiosis makes 4 genetically different cells make sperm and egg cells.
• mitosis makes 2 genetically identical daughter cells from one parent cell , whereas meiosis happens in any other cells
• what is the difference between mitosis and meiosis?

  mitosis produces 2 identical cells meiosis produces 4 different cells
• haploid is an organism cell that has half the number of chromosomes
• diploid is an organism cell that has a full set of chromosomes
• how many chromosomes does a human have?

  46
• GENES

  • are sections of DNA
  • are a code for a specific protein that gives characteristics
  • are inherited from our parents
  • genes come in different forms aka , ALLELES
• what are genes? (3)

  sectors of dna

  specific cell that gives protein and characteristics

  is inherited from our parents

  aka as allele
• are genes inherited from our parents? true or false?


  True
• what are genes aka?

  Genes are also known as DNA segments and alleles
• genes: sequences of dna that code for protein
• allele: different versions of the same gene
• homozygous: same alleles on each chromosomes, e.g. BB
• heterozygous: different alleles on each chromosomes, e.g. Bb
• dominant allele: more bigger allele with a capital letter, e.g BB
• recessive allele: less dominant allele , with lower case letters , e.g bb
• genotype: alleles
• phenotype: physical features
• define gene and an allele

  gene: a sequence of DNA that codes for protein

  allele: different versions of the same genes
• define homozygous and heterozygous

  homo: has same alleles on both chromosomes

  hetero: has different alleles on both chromosomes
• define dominant and a recessive allele:

  dominant allele: is the one that is expressed more in genetics

  recessive allele: is the one that is less expressed in genetics
• define genotype and phenotype:

  geno: are alleles

  pheno: are physical features
• what is the difference between homozygous and heterozygous?:

  the difference between them is that homo has the same alleles on both chromosomes whereas hetero has different alleles on both of them
• different versions of the same genes are called?

  Alleles
• alleles that are expressed more genetically are called?

  Dominant alleles
• alleles that are less expressed genetically are called?

  Recessive alleles
• dominant alleles have a _ letter in them , e.g BB
• recessive alleles have _ letter in them, e.g bb
• BB?


  dominant and is homozygous allele
• bb?


  recessive and homozygous allele
• Bb?


  heterozygous allele
• to find the probability of a gene , scientists use a probability method called "Punnet square"

  example:

  
• what is used to find the probability of a gene?

  Punnett square