biologyyyyy

• Ribosomes are responsible for protein synthesis in the cell.
• DNA is located in the nucleus of the cells apart from red blood cells
• DNA is inherited - passed on from generation to generation
• DNA is the genetic material of living things
• DNA is a long chemical sequence and this

  sequence contains the information for that

  living thing to develop, survive and pass on its

  genetic information to the next generation.
• The DNA chemical sequence differs between

  individuals. The pattern of this sequence is

  called the genotype.
• The sum total of all genetic information of

  an individual is the genome.
• DNA contains the genetic information (code)

  to make the specific proteins required by a

  cell.
• Proteins determine a cell’s structure,

  allowing it to perform its function (allowing

  the cells to differentiate)
• Copies of the cell’s genetic information are

  passed onto daughter cells during cell division
• Copies of a cell’s genetic information is

  passed on to the next generation when

  gametes fuse during fertilisation – the genetic

  code is inherited.
• Proteins contain the elements

  carbon, hydrogen, oxygen and

  nitrogen
• Proteins are large, insoluble

  molecules made up of a chain of

  smaller molecules called amino

  acids of which there are 20 types.
• Amino acids are joined together by

  peptide bonds.
• Structural proteins build proteins that form hair and cell membranes
• Enzymes speed up the rate of chemical reactions such as photosynthesis and respiration that are essential for life
• Hormones are chemical messengers eg insulin
• antibodies defend against antigens
• DNA has two strands

  coiled into a double helix.
• Each strand of DNA is made up of nucleotides
• Nucleotides are made up of three components: phosphate, deoxyribose and nitrogenous base
• The deoxyribose sugar is a pentose sugar –

  meaning it contains 5 carbons.
• Nucleotides are linked by their deoxyribose sugars and phosphates to form a strand with a sugar-phosphate backbone.
• DNA has 4 nitrogenous bases.
• Two strands of nucleotides are connected by hydrogen bonds between complementary base pairs.
• Adenine pairs with thymine and cytosine pairs with guanine
• The two DNA strands connect running in opposite directions
• Organisms fall into two main categories: prokaryotes and eukaryotes
• DNA is found in the cytoplasm in the form of a large singular circular chromosome or smaller rings called plasmids
• Prokaryotic cells also do NOT have membrane bound organelles [chloroplasts or mitochondria]
• Prokaryotic chromosomes have no introns and eukaryotic chromosomes have introns
• Small circular rings of DNA are found in the chloroplasts and mitochondria of eukaryotic cells
• Mitochondria are found in the cytoplasm of cells including ova
• The mitochondria genes code from the enzymes of aerobic respiration so mutations can be lethal
• Yeast is a unicellular fungus
• Yeast cells are unusual as they also contain some circular plasmids in their cytoplasm similar to those found in prokaryotes
• DNA replication ensures that an exact copy of a species genetic information is passed on from cell to cell during growth and from generation to generation during reproduction
• Each strand of DNA acts as a template for a new complementary strand so each DNA molecule formed during replication would be identical, each containing one ‘parental’ strand and one newly synthesised strand
• When the DNA in a chromosome is being replicated, many replication forks are formed at the same time. As a result, the DNA of whole chromosomes is replicated quickly and precisely
• Leading strand – replication of DNA from the 3’ end is continuous moving towards the replication fork