, TOPIC 1: LIFE AT MOLECULAR, CELLULAR & TISSUE LEVEL
Revision of Cells
● All living organisms have both DNA & RNA in their cells.
● DNA and RNA store genetic information and work together in replication and protein synthesis to
control the structure and functioning of living organisms.
● An organelle is a specialized structure inside a cell that performs a specific function needed for the
cell to survive and work properly. Certain organelles are play a big role in the production of protein
○ Cytoplasm- A jelly like substance and allows for metabolic reactions to take place.
○ Ribosome- Site of protein synthesis and consists of RNA & protein
○ Nucleus- Contains DNA & controls all of the cell’s activities
● The nucleus has 4 main parts
○ Double nuclear membrane- Encloses the nucleus and has pores that control movement of
substances in and out.
○ Nucleoplasm- Jelly like fluid of the nucleus
○ Nucleolus- A dense structure in the nucleoplasm that contains nucleotides and produces
ribosomes.
○ Chromatin network- Found in the nucleoplasm and contains DNA that forms chromosomes
carrying genetic information.
Structure of nucleic acids
● Nucleic Acid- Type of organic compound. There are 2 types
of nucleic acids in the human body, RNA & DNA
● Nucleotide: Monomer that forms DNA & RNA
DNA: Deoxyribonucleic Acid
● DNA carries the genetic code for protein synthesis
● It has the nitrogenous bases adenine, thymine, guanine & cytosine
● DNA is found in 2 locations
○ DNA found in the nucleus is referred to as nuclear DNA
○ A small bit of DNA called Extra-Nuclear DNA is found outside the nucleus. These are
Chloroplastic DNA & Mitochondrial DNA
The structure of DNA
● DNA has a coiled double helix structure, made of nucleotides which form long chains called
polymers. (the shape of DNA consists of two strands joined together and twisted spirally )
● The sugar of DNA is called deoxyribose sugar & is attached to a nitrogenous base.
● The phosphate & sugar are alternatingly attached to form a long chain
There are 4 types of nitrogenous bases
1. Adenine (A) 2. Cytosine (C)
3. Thymine (T) 4. Guanine (G)
1
, ● The nitrogenous bases of DNA
are complementary & always
join together in a specific order
○ Adenine links with
Thymine
○ Cytosine links with
Guanine
● The DNA strands wind around
proteins which are known as
histones.
The role of DNA
● DNA carries hereditary (genetic information passed on from parent to offspring) information
through genes.
○ Genes are short sections of DNA that code for specific traits and determine an organism’s
physical characteristics and some behaviours.
● Most DNA is non-coding and does not code for traits, and scientists are still researching its
function.
● The main DNA functions:
○ Controls the functioning of cells
○ Regulate the functioning of genes
○ Passes on hereditary characteristics
RNA: Ribonucleic Acid
● The main function of RNA is to make proteins in the cell
○ RNA consists of nucleotides. (Phosphate, Sugar & Nitrogenous bases) but unlike DNA, it has
uracil instead of thymine
● There are 3 types of RNA
○ Messenger RNA: mRNA carries the protein synthesis code from the DNA to the ribosome.
○ Ribosomal RNA: rRNA forms ribosomes (the site of protein synthesis)
○ Transfer RNA: tRNA brings amino acids to the ribosomes for protein synthesis
The location of RNA
mRNA: formed in the nucleus & enters the cytoplasm to attach to ribosomes
rRNA: found in the ribosomes in the cytoplasm
tRNA: free floating in the cytoplasm
The structure of RNA
● RNA is also made up for nucleotides, however it has a single stranded structure which isn’t coiled.
The sugar in RNA is called ribose
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Revision of Cells
● All living organisms have both DNA & RNA in their cells.
● DNA and RNA store genetic information and work together in replication and protein synthesis to
control the structure and functioning of living organisms.
● An organelle is a specialized structure inside a cell that performs a specific function needed for the
cell to survive and work properly. Certain organelles are play a big role in the production of protein
○ Cytoplasm- A jelly like substance and allows for metabolic reactions to take place.
○ Ribosome- Site of protein synthesis and consists of RNA & protein
○ Nucleus- Contains DNA & controls all of the cell’s activities
● The nucleus has 4 main parts
○ Double nuclear membrane- Encloses the nucleus and has pores that control movement of
substances in and out.
○ Nucleoplasm- Jelly like fluid of the nucleus
○ Nucleolus- A dense structure in the nucleoplasm that contains nucleotides and produces
ribosomes.
○ Chromatin network- Found in the nucleoplasm and contains DNA that forms chromosomes
carrying genetic information.
Structure of nucleic acids
● Nucleic Acid- Type of organic compound. There are 2 types
of nucleic acids in the human body, RNA & DNA
● Nucleotide: Monomer that forms DNA & RNA
DNA: Deoxyribonucleic Acid
● DNA carries the genetic code for protein synthesis
● It has the nitrogenous bases adenine, thymine, guanine & cytosine
● DNA is found in 2 locations
○ DNA found in the nucleus is referred to as nuclear DNA
○ A small bit of DNA called Extra-Nuclear DNA is found outside the nucleus. These are
Chloroplastic DNA & Mitochondrial DNA
The structure of DNA
● DNA has a coiled double helix structure, made of nucleotides which form long chains called
polymers. (the shape of DNA consists of two strands joined together and twisted spirally )
● The sugar of DNA is called deoxyribose sugar & is attached to a nitrogenous base.
● The phosphate & sugar are alternatingly attached to form a long chain
There are 4 types of nitrogenous bases
1. Adenine (A) 2. Cytosine (C)
3. Thymine (T) 4. Guanine (G)
1
, ● The nitrogenous bases of DNA
are complementary & always
join together in a specific order
○ Adenine links with
Thymine
○ Cytosine links with
Guanine
● The DNA strands wind around
proteins which are known as
histones.
The role of DNA
● DNA carries hereditary (genetic information passed on from parent to offspring) information
through genes.
○ Genes are short sections of DNA that code for specific traits and determine an organism’s
physical characteristics and some behaviours.
● Most DNA is non-coding and does not code for traits, and scientists are still researching its
function.
● The main DNA functions:
○ Controls the functioning of cells
○ Regulate the functioning of genes
○ Passes on hereditary characteristics
RNA: Ribonucleic Acid
● The main function of RNA is to make proteins in the cell
○ RNA consists of nucleotides. (Phosphate, Sugar & Nitrogenous bases) but unlike DNA, it has
uracil instead of thymine
● There are 3 types of RNA
○ Messenger RNA: mRNA carries the protein synthesis code from the DNA to the ribosome.
○ Ribosomal RNA: rRNA forms ribosomes (the site of protein synthesis)
○ Transfer RNA: tRNA brings amino acids to the ribosomes for protein synthesis
The location of RNA
mRNA: formed in the nucleus & enters the cytoplasm to attach to ribosomes
rRNA: found in the ribosomes in the cytoplasm
tRNA: free floating in the cytoplasm
The structure of RNA
● RNA is also made up for nucleotides, however it has a single stranded structure which isn’t coiled.
The sugar in RNA is called ribose
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