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topic 3 chemistry of life

Most frequently occurring elements in living things:

Carbon, Hydrogen, Oxygen, Nitrogen

Organisms require a small amount of other elements:

Sulfure, Calcium, Phosphate, Iron, Sodium

What does sulfur (s) do

Makes amino acids which create proteins

What is the use of calcium (ca)

Strong bones, acts as a messenger

What is Phosphate (p) needed for

To create ATP + DNA

What is the use of Iron (fe)

Needed for haemoglobin (which carries oxygen)

What is the structure of water

Polar molecule, Hydrogen Bonding

What is a polar molecule made up of

Negative oxygen end + Positive hydrogen end

How does hydrogen bonding occur

Between the hydrogen of one water molecule and the oxygen of another water molecule

What are the properties of water

Coolant, Transport, Habitat

Define water as a coolant:

·lots of energy required to heat
·when water evaporates energy is used -> cools organism

Examples of water as a coolant

Sweating, Panting, Transpiration

Define water as a transport

·Water is polar, universal solvent (liquid that dissolves solutes)
·Dissolves many organic and inorganic substances
·Movement of water carries substances around organism

Examples of water in transport

Xylem, Phloem, Adhesion, Cohesion

Explain Xylem

Nutrients from roots to tree

Explain Phloem

Nutrients from tree to roots

Explain Adhesion

Two different substances attaching

Explain Cohesion

The same substances attaching

Define water as a habitat

Water is transparent
Allows light through for photosynthetic organisms
Organisms live in or on water because of surface tension
Contains dissolved gases
Aquatic organisms survive under ice at surface

What is surface tension


Organic compounds

Compounds found (built) in living things (organisms

Inorganic compounds

NOT found in living organisms

Major molecules

Amino acids, Glucose, Ribose, Fatty acids

3 types of saccharides

Monosaccharides, Dissacharides, Polysacharides

Examples of Monosaccharides

Glucose, Fructose, Galactose

Examples of Dissacharides

Maltose, Lactose, Sucrose

Examples of Polysaccharides

Starch, Glycogen, Cellulose

Which saccharides are in Animals

Glucose, Lactose, Gylcogen

The role of glucose in animals

Carried by blood to transport energy to cells throughout the body

The role of lactose in animals

The sugar in milk provides energy to young mammals until they are weaned

What is the role of glycogen in animals

Used as a short-term energy and is stored in liver and muscles

Which saccharides are in Plants

Fructose, Sucrose, Cellulose

What is the role of Fructose in plants

Used to make fruits sweet tasting, attracting animals to disperse seeds in the fruit

What is the role of Sucrose in plants

Carried by phloem to transport energy to cells throughout the plant

What is the role of Cellulose in plants

Used to make strong fibers that are used to construct the plant cell wall

Hydrolysis reaction is adding:


What is used up during hydrolysis reactions

Water Molecules

What is the reverse of condensation reactions

Hydrolysis reactions

Polypeptide + Water =

Dipeptides or amino acids

Polyssacharides + Water =

disaccharides or monosaccharides

Glycerides + Water =

Fatty acids + gylcerol

Function of lipids

Energy storage,Thermal (heat) insulation, Bouyancy

Function of energy storage in lipids

Energy storage in the form of fat in humans and oil in plants

Function of thermal insulation in lipids

A layer of fat under the skin reduces heat loss

Function of buoyancy in lipids

Lipids are less dense than water so help animals to float

What contains more energy per gram: carbohydrates or lipds


What kind of energy storage are lipids typically used for

Long term storage

What kind of energy storage are carbohydrates typically used for

Short term storage

Are lipids insoluble or soluble


Lipids are insoluble so they dont cause problems with:

Osmosis in cells

What is more easily digested carbohydrates or lipids


Carbohydrates can be easily digested therefore:

Energy stored can be released more rapidly

Are carbohydrates soluble or insoluble


Carbohydrates are soluble therefore

easier to transport to and from the store

3 parts to a DNA nucleotide

Sugar, Base, Phosphate

3 bases in DNA nucleotide

Adenine (A) Cytosine (C) Guanine (G) Thymine (T)

How are DNA nucleotides linked

by covalent bonds into a single strand

Where does the covalent bond occur

Between deoxyribose and phosphate group

DNA double helix is formed using

Complimentary base pairing and hydrogen bonds

Adenine is paired with


Cytosine is paired with


How many stages are there in the process of DNA replication


Stage 1 of DNA replication

Double helix unwinds and separates into strands (because of breaking of hydrogen bonds)
Helicase (enzyme) separates strands by breaking bonds

Stage 2 of DNA replication

Single strand act as templates for new strands
Free nucleotides are present for building
Bases of these nucleotides form hydrogen bonds with bases of parent strand
Nucleotides are linked up to form new strand
DNA polymerase is the enzyme used to create new complimentary strands

Stage 3 of DNA replication

Daughter DNA molecules each rewind into a double helix

Complementary base pairing allows

for conservation of the base sequence of DNA

What does semi-conservative mean

Each molecule is formed by replication
Consist of one NEW strand + one OLD strand conserved from parent DNA molecule

How many strands in DNA

2 strands

How many strands in RNA


Bases in RNA nucleotide

Adenine (A)
Cytosine (C)
Guanine (G)
Uracil (U)

Sugar used in DNA


Sugar used in RNA


Why do we make mRNA

Messenger to go into the cytoplasm and make proteins

What is transcription

Process of making mRNA

What does tRNA mean

Transfer RNA

What does rRNA mean

Ribosomal RNA

RNA is ? stranded


What is the point of transcription

DNA is an important molecule -> dont want to damage it

RNA ? does everything in transcription

RNA Polymerase

Steps of transcription

RNA Polymerase bind to a site called the 'promoter' on DNA
DNA strand separated by RNA polymerase on specific part of gene to be transcripted
RNA nucleotides pair with complementary bases on one strand of DNA only
RNA polymerase forms covalent bonds between nucleotides
RNA seperates from DNA and double helix forms

What is translation

Process of protein production using mRNA as a guide

Genetic code:

'translation dictionary' that enables cells to convert base sequences on the mRNA into an amino acid sequence

What is a codon

Sequence of 3 bases on the mRNA

What is tRNA

Transfer RNA that carried amino acids

Where does translation take place:


Where are Ribosomes found:

In Cytoplams, outside the Nucleus

Each ribosome has a large and small ?:


Ribosomes make->


Process of translation:

mRNA binds to small subunit of ribosome (5'->3') direction
tRNA molecules present, each one carrying specific amino acid corresponding to anti-codon
tRNA binds to ribosome at the site where its anti-codon matches the codon on the mRNA
2 tRNA bind at once, 1st transfers

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