yr 10 science 2024

• genetic variation

  small differences in genes that make each organism unique
• genotype

  traits in GENES
• phenotype

  OBSERVABLE or PHYSICAL traits
• wild type

  the most common phenotype for a particular trait in a particular population
• mutant

  low frequency traits
• a change in the amino acid sequence CAN increase the risks of CANCER
• nucleotides code for amino acids
• A - T
• C - G
• nucleotides are the strands that are on DNA
• 28 trillion cells are in your body
• DNA molecules are very tightly packaged into chromosomes


  a SINGLE chromosome is made up of a SINGLE DNA molecule
• gene

  sections of DNA that CONTAINS info for some characteristic/trait or FUNCTION of an organism
• GENES code for TRAITS/CHARACTERISTICS
• chromosome - threadlike structures containing the DNA

  
• chromosome = DNA + histone proteins
• chromosomes ensure that DNA is replicated and distributed correctly when the cell divides in two
• sister chromatids

  two IDENTICAL copies of a chromatid
• chromatin

  the mass of genetic material in the nucleus
• chromosomes are matched up according to LENGTH, POSITION and the SAME GENES in the SAME PLACES
• human cells have 46 chromosomes, arranged in 23 pairs
• egg cell and sperm cells have 23 chromosomes each
• each chromosome has two copies - one from each parent
• the first 22 pairs of chromosomes are known as AUTOSOMES
• the last pair of the 23 chromosomes are called the sex chromosomes(ALLOSOME)


  bio female = XX

  bio male = XY

  XXY = male with reduced puberty symptoms
• X chromosome is bigger than the Y chromosome


  Y chromosome contains less genes
• karyotype

  organised profile of an individuals CHROMOSOMES

  • size from LARGEST to SMALLEST (1-22)
• nucleotide consists of sugar, phosphate group and nitrogenous base
• allele

  alternative form of a gene

  • inherits one allele for each gene pair from each parent for each trait
• alleles for the SAME gene are found in the same position (LOCI) on a chromosome
• codominance

  a pattern of dominance where BOTH alleles from the genotype of a HETEROZYGOUS individual are DOMINANT and seen physically on the individual.
• incomplete dominance


  a pattern of dominance where NEITHER allele from a genotype of an individual is DOMINANT and are BOTH seen physically as a MIX
• autosomal dominant traits

  ONE mutated copy of the gene is enough for a person to be affected by the disorder or condition
• autosomal recessive traits

  BOTH copies of the gene in the individual have mutations in order to make the individual affected
• sex-linked inheritance

  some traits are inherited on the X-chromosome
• pedigree

  a diagram that shows the inheritance of a trait from one generation to the next
• DNA


  contains genetic information