science

• (A)adenine (A) thymine (T) cytosine (C) guanine
• The DNA has a structure similar to a double helix which kinda looks like a twisted rope ladder.
• (A)adenine (T) thymine (C) cytosine (G) guanine are called nucleotides
• (T)thymine only goes with (A) adenine and (G) guanine goes only with (C) cytosine
• DNA is found in our chromosomes
• Chromosomes are structures found in the nucleus of all cells in the body except red blood cells.
• Genes are made from DNA and they control everything about us including our height, eye colour, hair colour etc.
• DNA contains genetic information that determines how we look, what we can do and who we will be when we grow up.
• different versions of the same genes are called alleles or different variations of a gene e.g. yellow/green eye color
• genotype = combination of alleles inherited by an individual
• allele = different version of gene
• phenotype = physical appearance determined by genotype
• dominant trait = one version of a gene which masks another version so it cannot be seen
• recessive trait = one version of a gene which does not show unless both copies of the gene are recessive
• recessive traits are not expressed unless both copies are present such as yy if there was a dominant Y gene then the phenotype will be the dominant gene
• dominant trait is always expressed even if only one copy present such ad Yy where Y will show. Say that Y was having colored eyed and y was not but the phenotype will be colored eyes as dominant dominates the recessive genes.
• recessive trait = one version of a gene that is only expressed when both copies of a gene are recessive
• heterozygous dominant = one dominant allele, one recessive allele(hybrid, not pure such as Yy)
• homozygous dominant = two identical versions of a gene (one from mum, one from dad) bascially basically pure genes such as YY or yybasically
• If both parents have long eyelashes and their child doesn't that means they are a carrier for small eyelashes and their genotype would be Ee
• mitosis: a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth so basically a clone of a gene.
• meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information and has 4 daughter cells .
• punnet square- used to show the inheritance of traits from parents to offspring

  A) dominant gene

  B) recessive gene

  
• dominant trait isn't equal to a more common trait as a recessive gene of not having long eyelashes is pretty common
• body cells= somatic cells ( cells in the body other than sex cells)
• sex cells= gametes (sperm and egg)
• there are two types of cell division: mitosis and meoisis
• mitosis produces identical copies of parent cells, while meiosis produces genetically different cells.
• the nucleus contains chromosomes which contain genes that determine characteristics such as eye colour or height
• meiosis occurs only in reproductive organs, while mitosis can occur anywhere in the body.
• in mitosis, chromosomes duplicate themselves first, then separate into daughter nuclei, resulting in two identical daughter cells with the same number of chromosomes as the original cell. In contrast, during meiosis, there are two rounds of nuclear division that result in four haploid daughter cells with half the number of chromosomes compared to the original cell.
• A human has 46 chromosomes in total with 23 given by a single parent