Terms in this set (87)
Name the four typical tissue types in the human body.
Name the 11 major organ systems.
What are the six main elements in our body?
O, C, H, N, Ca, P
What is an isotope?
Elements that differ in the number of neutrons. Do not change the chemical behaviour.
Radioisotopes (unstable isotopes) decay to stable isotopes, releasing radiation
What are alpha, beta and gamma particles?
Alpha: 2P + 2N ~ can't penetrate skin
Beta: free electron, penetrates skin a few mm
Gamma: high energy, penetrating; very dangerous
Time for 50% of atoms to decay
The transfer of electrons from one atom to another. Increases stability of valence shell.
Does an anion or cation have a net negative charge?
What are electrolytes?
Salts that ionise in water, form solutions capable of conducting electricity.
What are our body's more abundant electrolytes?
Na+, Ca2+, Mg2+, Cl-, HCO3-
What is a free radical?
A particle with an odd number of electrons.
What is a structural isomer?
Molecular formulae are identical but the structures and chemical properties are different
Describe ionising radiation?
High energy, ejects electrons from atoms. Destroys molecules and produces free radicals.
What is an alpha particle?
2 protons + 2 neutrons. Can't penetrate skin.
What is a Beta particle?
Free electron. Penetrates skin a few millimetres.
What is a gamma particle?
High energy, penetrating; very dangerous.
What is a free radical?
A particle with an odd number of electrons. Produced by metabolic reactions, radiation, chemicals. Causes tissue damage.
What neutralises free radicals?
Define an ionic bond.
Attraction of oppositely charged ions to each other, no sharing of electrons. They are weak and dissociate in water.
Describe covalent bonds.
Formed by sharing valence electrons. Can be non polar (electrons shared equally) or polar (electrons shared unequally).
Describe hydrogen bonds.
Attraction between polar molecules, no sharing of electrons. Weakest of the bonds.
What is a monomer?
Subunits of macromolecules.
What is polymerisation?
The bonding of monomers together to form a polymer. This is caused by a reaction called dehydration synthesis.
What is dehydration synthesis?
Monomers bond together to form a polymer (synthesis), with the removal of a water molecule (dehydration)
What is hydrolysis?
Splitting a polymer by the addition of a water molecule.
If an R group is polar, is it hydrophobic or hydrophilic?
What is an essential amino acid and how many are considered essential for humans?
An amino acid that cannot be synthesised by the organism and therefore must be supplied in our diet. 9 are considered essential for humans.
Describe peptide bonds.
Join amino acids together by losing one molecule of water.
How many peptides are in a polypeptide and what can these also be called?
About 40. Large polypeptide molecules are called proteins.
How are peptide chains named?
From the free N (NH2) end to the free C (COOH) end.
Describe a primary protein structure.
Linear sequence of amino acids forming polypeptide chains. Known as the backbone of the protein molecule.
Describe a secondary protein structure.
The chain of amino acids twists or bends due to weak hydrogen bonds. They most commonly form an alpha-helix or beta pleated sheet.
Describe a tertiary protein structure.
Alpha-helix and beta pleated sheet regions fold around/over one another to form new shape. 3-dimensional.
Describe a quaternary protein structure.
Made of 2 or more polypeptide chains interacting together. Each polypeptide is known as a subunit of the protein. Haemoglobin is an example of a quaternary structure.
Structure gives rise to two main types of proteins. What are these?
Fibrous and globular.
Describe fibrous proteins.
Linear and strand-like. Most have only secondary structure, some have quaternary. They are insoluble in water, very stable and provide mechanical support. Structural proteins. E.g. Collagen, keratin, contractile proteins of muscle.
Describe globular proteins.
Compact and spherical. All have at least tertiary structure, some have quaternary. Water soluble, mobile and chemically active. Functional proteins - have roles in biological processes. E.g. Antibodies, some hormones, enzymes.
What is denaturation?
Loss of secondary/tertiary structure due to chemical and physical forces such as heat and acidity. Disrupts bonds between amino acids. In mild cases is it reversible.
What happens when globular proteins denature?
They cannot perform their physiological roles as they depend on active sites on their surfaces to function normally.
What is a carbohydrate?
Hydrophilic, organic molecule containing C, H and O. Commonly called sugars and starches.
What is the general formula of carbohydrates?
H and O occur in a 2:1 ratio
What is a monosaccharide?
Single chain or ring structure with 3-7 carbon atoms. C, H and O atoms occur in a 1:2:1 ratio.
E.g. Glucose, fructose, galactose, deoxyribose, ribose.
What are three major disaccharides?
Sucrose (glucose + fructose)
Lactose (glucose + galactose)
Maltose (glucose to glucose)
What are disaccharides?
Two simple sugars joined together by losing a water molecule (dehydrated synthesis). Can break up by adding water to form the simple sugars again (hydrolysis).
How many monosaccharides units are in an oligosachharide?
What are polysaccharides?
Simple sugars linked by dehydration synthesis. Form long chain-like units called polymers.
A polysaccharide. Plants store glucose as starch. It is made up of two types of glucose polymer:
1. Amylose (a linear molecule)
2. Amylopectin (similar to amylose but has side chains)
Animals store excess sugar in the form the polysaccharide glycogen. When glucose cannot be stored as glycogen or used immediately for energy, it is converted to fat. It is similar to amylopectin, but the branches tend to be shorter (about 13 glucose units) and more frequent. Glycogen is easily converted back to glucose to provide energy.
Most abundant organic compound on earth. It forms cable-like fibrils in the tough walls that enclose plant cells. Major component of wood. Grazing animals survive a diet of cellulose because they have bacteria in their digestive tracts that can break it down.
Where is chitin found and what polysaccharide is it similar in structure to?
In fungal cell walls. Similar structure to cellulose.
What are the three major functions of carbohydrates?
1. Source of energy (starch, glycogen)
2. Structural (cellulose, chitin)
3. Conjugated carbohydrates
Glycolipids, glycoproteins, proteoglycans.
Hydrophobic (non-polar) organic molecules. Less oxidised than carbohydrates, have more calories per gram.
What are the five primary types of lipids?
What are fatty acids?
Chain of usually 4 to 24 carbon atoms. Carboxyl acid group on one end, methyl group on the other. Polymers of two-carbon acetyl groups.
What is the difference between saturated and unsaturated fatty acids?
Saturated: carving atoms saturated with hydrogen.
Unsaturated: contains C=C bonds that could bond more hydrogen.
What do the double bonds of unsaturated fatty acids do in oils (liquid)?
Introduce bends in the hydrocarbon tail and inhibit close packing.
How are triglycerides formed?
By dehydration synthesis
What is the most concentrated source of energy?
Describe triglycerides at room temperature.
Liquid called oils, often polyunsaturated fats from plants.
Solid called fat, saturated fats from animals.
What are the functions of triglycerides?
Shock absorption for organs.
Are triglycerides soluble or insoluble in water?
Insoluble. The long hydrocarbon chains of fatty acids contain only nonpolar C-H bonds, which are unable to interact with water.
What does amphipathic mean?
Has both hydrophilic and hydrophobic parts.
Hydrophobic ends similar to neutral fats with two fatty acids attached to glycerol.
Hydrophilic ends differ from neutral fat with the third fatty acid replaced with phosphate group attached to other functional groups.
What are eicosanoids?
Derived from arachidonic acid (a fatty acid). Function as chemical signals between cells. Includes prostaglandins.
What is cholesterol?
What other steroids are derived from cholesterol?
Cortisol, progesterone, oestrogen, testosterone and bile acids.
What is cholesterol required for?
Proper nervous system function and is an important component of cell membranes.
What are the two main types of nucleic acids?
RNA (mRNA, tRNA, rRNA)
What does a nucleotide consist of?
A phosphate group
A 5-C sugar
A nitrogenous base
What are two differences between DNA and RNA?
DNA contains a sugar group with a 2' hydrogen, while RNA contains a 2' hydroxyl group.
DNA contains thymine, RNA contains uracil (lacks a methyl group).
What are the pyramidines of DNA?
Thymine and Cytosine.
Adenine and guanine are purines.
What sort of bonds form a polynucleotide?
Nucleotides covalently bond to form a polynucleotide
Does DNA begin at the 3' or 5' end?
How many nucleotides code for 1 amino acid?
What is codon?
Mirror image sequence of nucleotides in mRNA
What is the start codon?
Where are hydrogen bonds in nucleotides?
Between base pairs.
2 H-bonds between A and T
3 H-bonds between C and G
What are exons and introns?
Exons: Coding portions of the gene
Introns: non-coding portions. Are edited out of final mRNA
What does DNA helicase do?
The enzyme that opens a short segment of helix.
What does DNA polymerase do?
Allows strands to be replicated in opposite directions.
What joins segments of the lagging strand?
What does semi-conservative replication mean?
Each new DNA molecule has one new helix with the other helix conserved from patent DNA
What is a promoter?
Regions of DNA that facilitate transcription of a particular gene.
What is transcription?
The first step of gene expression, in which a particular segment of DNA is copied into mRNA by the enzyme polymerase.
What is DNA translation?
The process of translating the sequence of a mRNA molecule to a sequence of amino acids during protein synthesis.
What end of the strand are nucleotides added?