Lecture 2 : Cellular Biology Overview

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Lecture 2 Cellular BiologyOverview

• CLASSIFICATION GENUS AND SPECIES
• CELLULAR BIOLOGY
• Cell Structure
• Cell Respiration
• Deoxyribonucleic Acid (DNA)
• Chromosomes And Genes
• Protein Synthesis
• Mitosis

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Genus And Species

• Organism A lifeform.
• Species Organisms sharing certain
  characteristics and capable of interbreeding.
• Genus Species sharing common characteristics.
• Syntax Genus species e.g. Homo sapiens.
• Higher levels Kingdom, phylum, class, order,
  family.
• Kingdoms Animals, plants, monerans, protists
  and fungi.

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Cells

• Humans have approximately 1014 cells.
• Cells are organised into tissues, which form
  organs,which and linked into systems.
• Each cell measures about 10-5 m.
• Animals cells have a nucleus containing DNA,
  surrounded by cytoplasm and an outer membrane.
  The cytoplasm contains organelles (e.g. ribosomes
  and mitochondria).

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Cell Respiration

• Food is broken down by enzymes into simpler
  compounds.
• Protein is broken into amino acids.
• Carbohydrates are broken down to glucose.
• Fats are broken down into glycerol and fatty
  acids.
• Energy is released when mitochondria combine
  glucose with oxygen to produce carbon dioxide and
  water
• C6H12O6 6O2 ? 6CO2 6H2O

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Deoxyribonucleic Acid (DNA)

• Each cell contains an identical copy of DNA.
• Comprised of a long string of nucleotides.
• Each nucleotide consists of a deoxyribose sugar
  molecule linked to a phosphate group and to one
  of four types of base.
• The sugars and phosphates form the spiral shaped
  backbones, while the bases are joined in pairs to
  form the steps.

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DNA Bases

• The 4 types of base are identified by their
  capital letter A (adenine), C (cytosine), G
  (guanine) and T thymine).
• Bases line up A with T and C with G to form steps
  in a spiral staircase.
• Human DNA contains about 3 million base pairs.
• Each cell contains about 25mm of DNA packed into
  a nucleus about 1/1,500th mm across.

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Chromosome And Genes

• Human DNA is grouped into 46 chromosomes.
• A gene is a sequence of nucleotide bases at a
  particular location (locus) which codes for a
  specific protein.
• Human DNA contains between 20,000 and 30,000
  genes.
• Genes vary in length from around 100 to several
  million base pairs.
• Each individual has a unique set of genes.

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Protein Synthesis (1)

• Proteins perform numerous functions.
• Proteins are large molecules made up from 20
  types of amino acid which may be combined in any
  sequence.
• Some amino acids can be manufactured by the body,
  but 8 essential amino acids must come from the
  diet.
• The sequence in which the amino acids are joined
  is specified by DNA.
• Each amino acid is specified by a group of 3
  bases known as a triplet or codon.

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Protein Synthesis (2)

• The relevant part of the DNA molecule unzips down
  the middle.
• The exposed bases join with RNA bases to form
  messenger RNA.
• Messenger RNA exits the nucleus.
• A ribosome reads the RNA like a ticker tape and
  joins the specified amino acids to build the
  protein.

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Mitosis

• Growth occurs by cells becoming more numerous,
  not larger.
• Cells divide by a process known as mitosis.
• Before the cells divide, the DNA splits down the
  middle, and each base combines with a free
  complementary DNA base in the nucleus.
• This produces two complete sets of identical
  chromosomes.

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N.B. Diagram only shows 2 of the 46 chromosomes