T1 Bio

• Chromosomes contain DNA, which stores all of the genetic information for an organism.
• Inherited traits are coded in your DNA, and come from your biological parents.
• Aquired traits develop during life and are not in DNA so cannot be passed on
• Genes control the development of one or more traits, and are a unit of DNA located on a chromosome
• Proteins are chains of amino acids joined together and then twisted. Come from food or are made in the human body. Used to create muscles, hormones, enzymes and anti-bodies.
• DNA is packaged into 46 chromosomes (23 pairs of chromotids) in the nucleus of the cell
• Each chromosome is made of one strand of DNA coiled tightly around histones. Each chromosome contains a large number of genes
• Chromosome pairs 1-22 are autsome. Pair 23 are sex chromosomes
• Aneupliody is when chromsomes either have extra or missing chromosomes, significantly changing the person's genetic identity
• mRNA -> amino acids -> polypeptide chains -> proteins
• A mutation is a process that makes a permanent change in a DNA sequence. They are either spontaneous or induced
• Spontaneous mutations are random changes in the DNA sequence that occur during replication.
• Induced mutations can be caused by a variety of factors including carinogens (harmful substances) and radioactivity
• What are the three types of mutations?

  Substitution, deletion, insertation
• Asexual reproduction creates an identical genetic copy (mitosis)
• Sexual reproduction creates a unique combination of alleles in each offspring (two gametes fuse).
• Mitosis is when a single cell divides into two cells and makes new body cells. These cells are identical, and are growth, repair and asexual reproduction (binary fission)
• What are the phases of mitosis?


  Interphase, prophase, metaphase, anaphase, telophase, cytokinesis
• Interphase

  Growth, DNA replication, DNA duplication, cell function
• Prophase


  Nucleus is present, chromosomes are condensing
• Metaphase


  Nucleus de-assembles, chromosomes are in the middle
• Anaphase


  Sister chromotids seperate, move to the two poles
• Telophase

  Two new nuclei form
• Cytokinesis


  Cells split into cytoplasm and into two cells
• Meiosis is the process of cell division to form sperm and egg cells (gametes), and contributes to genetic variation
• Meiosis stages are prophase, metaphase, anaphase, and telophase. These all happen twice. Creates 4 different cells
• An allelle are different forms of the same gene
• A genotype is the alleles that you have (BB)
• A phenotype is how it actually appears (BB = brown eyes)
• Homozygous alleles are the same (bb, BB)
• Heterozygous alleles are different. One will be stronger/more dominant than the other. (Bb)
• Dominant alleles are the stronger alleles that will mask the recessive allele
• Recessive alleles are masked by the dominant alleles
• Incomplete dominance is where the dominant allele does not completely mask the recessive allele, leading to a blended appearance. More than 2 phenotypes can occur
• Codominance is where two alleles are expressed equally. Neither is dominant nor recessive.
• Sex linked inheritance is when a trait is controlled by a gene on the X chromosome.
• Mutated genes on the sex chromosomes are sex-linked genetic disorders
• Hemophilia is an example of a sex-linked disorder as it affects males more often due to being carried on the x chromosome
• The probability of inheriting a particular genotype depends on how many copies of the allele they have inherited from their parents
• Punnett squares show all possible combinations of genotype from parents' gametes