Genetics: Life at Molecular, Cellular and tissue level
Summary of Genetics Definitions: (35)
● DNA: Deoxyribonucleic Acid which is responsible for replication of material
(chromosomes) present in organisms. Carrier of genetic information.
● RNA: Ribonucleic Acid which acts as a messenger and carries instructions from DNA for
protein synthesis.
● Chromatin: chromosomal material made up of DNA, RNA and histone proteins found in a
non-dividing cell.
● Replication: the process of making a new DNA molecule from an existing DNA molecule
that is identical to the original molecule
● Transcription: DNA makes and codes for mRNA
● Codon: assortment of 3 nucleotides forming a genetic code which codes for amino acid
● Stop-Codon: 3 nucleotides which do NOT code for amino acid
● Mutation: any alteration in genetic makeup of organism
● Mutagen: physical or chemical agent speeding up mutation
● Gene Mutation: a small localised change in structure of DNA strand
● Point Mutation: change in single nucleotide
● Substitution: one nucleotide exchanged for another in DNA molecule
● Insertion: one or an extra nucleotide is inserted into DNA molecule
● Deletion: a nucleotide is removed from DNA molecule
● DNA profile: an individual's unique DNA fragments separated by electrophoresis
● Chromosome: a long, thread-like structure that makes up the chromatid network in nuclei
of cell. Are made up of strand of DNA wound around proteins called histones.
● Sex Cell: 46 chromoyyyyyfffgsomes (23 and 23)
● Somatic Cell: body cell (diploid) 23
● Diploid: 2 sets of chromosomes
● Haploid: 1 set of chromosomes (1 in each daughter cell, when gametes fuse = 2)
● Meiosis: cell division takes place in reproductive organs of both plants and animals to
produce gametes in animals and spores in plants.
● Crossing over: mutual exchange of parts of chromosome where maternal and paternal
information is shared.
● Chiasmata (breaking of parts of chromatin)
● Bivalent formed via synapsis (when chromosomes meet)
● Chromosomal nondisjunction: chromosomes fail to separate properly
● Aneuploidy: extra or missing chromosome (e.g: down syndrome = extra chromosome
21, trisomy)
● Karyotype = set of chromosomes in cell
● Autosomes = non-sex chromosomes (human)
● Sex chromosome = gonosome
, ● Genetics: the study of heredity and genetic variation
● Alleles: genes responsible for different variations of a trait found in the same locus on
homologous chromosomes.
● Gene: section of DNA that controls a hereditary characteristics and codes for a specific
function
● Father of genetics = gregor mendel
● Gene Pool: set of genes in sexually reproductive organisms
● Genotype: gene of an organism that carries chromosomes which is inherited by parents.
● Phenotype: physical appearance. Programmed by genes in genotype and outside
factors.
● Genome: complete set of genetic instructions necessary to create an organism
● Harmful: chromosomal mutation
● Beneficial: change in phenotype (adaption)
● Neutral: doesn’t affect organism
DNA: Structure and coding (SAGS Breakdown:)
➔ How the work done by many scientists allowed Watson and Crick to unravel the
genetic code (1953) and, in the 1960s the mechanism of protein synthesis and
DNA replication.
➔ The structure and location of DNA and RNA (mRNA, tRNA) in a cell
➔ Simple structure of nucleotides, including names of the four nitrogenous bases of
DNA (adenine = A, thymine = T, cytosine = C, guanine = G) and that uracil replaces
thymine in RNA and which bases are complementary
➔ Mitochondrial DNA also exists and remains unaltered from mother to child. That
this is used to determine relatedness.
Background (Understand):
● Nucleic acids = molecules of life
● They have the capacity to store information that controls cellular activity and
development of entire organism
● They do this by controlling the synthesis of proteins
● Proteins: make up structure of body + control chemical processes inside cells (enzymes
are proteins)
● Proteins ultimately control structure + functioning of all living organisms
● Two nucleic acids:
- Deoxyribonucleic acid (DNA)
- Ribonucleic acid (RNA)
Who Discovered the Structure of DNA (SAGS):
, ● King’s College, London (early 1950s): Maurice Wilkins and Rosalind Franklin were trying
to work out structure of DNA
● Took experimental approach: looked at X-ray crystallography (diffraction images of DNA)
● At same time at Cavendish Institute (Cambridge University) graduate students Francis
Crick and research fellow James Watson also became interested in determining the
structure of DNA
● They analysed the x-ray data collected by Rosalind Franklin and others
● They built a model out of brass plates and clamps and other bits of laboratory equipment
and realised that nucleic acids are arranged like a twisted ladder (with 2 runners made of
phosphates and sugars and a series of rungs made of pairs of organic compounds
known as bases)
Genetic Replication (unravelling of genetic code) (SAGS):
● Watson and Crick developed ideas about genetic replication in a second article in
Nature, published May 30th 1953
● Pairing of bases (A with T and C with G) showed that ---> given a sequence of bases in
one strand, the other strand was automatically determined
● This meant that when two strands separated, each served as a template for a
complimentary new chain (thus each strand could replicate)
● After ‘double helix’ model, there were still Q’s about how DNA directs the synthesis of
proteins
● 1961: Francis Crick and Sydney Brenner provided genetic proof that a Triplet code was
used in reading genetic material in DNA and transferring the information from nucleus to
cytoplasm via RNA to where proteins are made
● The two showed that in DNA- form is function: double-stranded molecule could both
produce exact copies of itself (replicate) and carry genetic instructions
● Thus the sequence of bases in DNA forms a code by which genetic information can be
stored and transmitted
Who Won The Nobel Prize (understand):
● Rosalind Franklin: only researcher with a degree in chemistry
● Worked alone and suspected (through her x-ray diffractions) that all DNA molecules
were helical in structure but she was reluctant to announce this finding until she had
sufficient evidence
● She died of cancer at 37, before expressing her views
● 1962: Watson, Crick and Wilkins won nobel prize for physiology/medicine (Franklin was
dead)
● Nobel prize only goes to living recipients and can only be shared among 3 winners
● Would she have received the prize if she were alive though? (women in era, oppressed
and not recognised)
, DNA:
The Location of DNA (SAGS):
● Found mainly in the nucleus of a cell where it forms an important part of chromosomes
that make up chromatin network
● Chromatin: chromosomal material made up of DNA, RNA and histone proteins found in
a non-dividing cell
● DNA molecule, coiled so that these long structures can fit inside nucleus (2m of DNA in
every cell)
Extracellular DNA (understand):
● Small amounts of DNA found outside the nucleus in: mitochondria in plants and
animals as well as in chloroplasts in plants
The Structure of DNA (SAGS):
● Shape: long, twisted ladder. Two strands twist to form stable, 3-dimensional double
helix.
What Units Make Up DNA (SAGS):
● DNA molecule: long chain (polymer) made of small units (monomers) i.e: building blocks
called nucleotides. Each nucleotide is made up of a:
❏ Deoxyribose (sugar molecule)
❏ Phosphate molecule (P)
❏ Nitrogenous base which may be:
- Adenine (A)
- Thymine (T)
Summary of Genetics Definitions: (35)
● DNA: Deoxyribonucleic Acid which is responsible for replication of material
(chromosomes) present in organisms. Carrier of genetic information.
● RNA: Ribonucleic Acid which acts as a messenger and carries instructions from DNA for
protein synthesis.
● Chromatin: chromosomal material made up of DNA, RNA and histone proteins found in a
non-dividing cell.
● Replication: the process of making a new DNA molecule from an existing DNA molecule
that is identical to the original molecule
● Transcription: DNA makes and codes for mRNA
● Codon: assortment of 3 nucleotides forming a genetic code which codes for amino acid
● Stop-Codon: 3 nucleotides which do NOT code for amino acid
● Mutation: any alteration in genetic makeup of organism
● Mutagen: physical or chemical agent speeding up mutation
● Gene Mutation: a small localised change in structure of DNA strand
● Point Mutation: change in single nucleotide
● Substitution: one nucleotide exchanged for another in DNA molecule
● Insertion: one or an extra nucleotide is inserted into DNA molecule
● Deletion: a nucleotide is removed from DNA molecule
● DNA profile: an individual's unique DNA fragments separated by electrophoresis
● Chromosome: a long, thread-like structure that makes up the chromatid network in nuclei
of cell. Are made up of strand of DNA wound around proteins called histones.
● Sex Cell: 46 chromoyyyyyfffgsomes (23 and 23)
● Somatic Cell: body cell (diploid) 23
● Diploid: 2 sets of chromosomes
● Haploid: 1 set of chromosomes (1 in each daughter cell, when gametes fuse = 2)
● Meiosis: cell division takes place in reproductive organs of both plants and animals to
produce gametes in animals and spores in plants.
● Crossing over: mutual exchange of parts of chromosome where maternal and paternal
information is shared.
● Chiasmata (breaking of parts of chromatin)
● Bivalent formed via synapsis (when chromosomes meet)
● Chromosomal nondisjunction: chromosomes fail to separate properly
● Aneuploidy: extra or missing chromosome (e.g: down syndrome = extra chromosome
21, trisomy)
● Karyotype = set of chromosomes in cell
● Autosomes = non-sex chromosomes (human)
● Sex chromosome = gonosome
, ● Genetics: the study of heredity and genetic variation
● Alleles: genes responsible for different variations of a trait found in the same locus on
homologous chromosomes.
● Gene: section of DNA that controls a hereditary characteristics and codes for a specific
function
● Father of genetics = gregor mendel
● Gene Pool: set of genes in sexually reproductive organisms
● Genotype: gene of an organism that carries chromosomes which is inherited by parents.
● Phenotype: physical appearance. Programmed by genes in genotype and outside
factors.
● Genome: complete set of genetic instructions necessary to create an organism
● Harmful: chromosomal mutation
● Beneficial: change in phenotype (adaption)
● Neutral: doesn’t affect organism
DNA: Structure and coding (SAGS Breakdown:)
➔ How the work done by many scientists allowed Watson and Crick to unravel the
genetic code (1953) and, in the 1960s the mechanism of protein synthesis and
DNA replication.
➔ The structure and location of DNA and RNA (mRNA, tRNA) in a cell
➔ Simple structure of nucleotides, including names of the four nitrogenous bases of
DNA (adenine = A, thymine = T, cytosine = C, guanine = G) and that uracil replaces
thymine in RNA and which bases are complementary
➔ Mitochondrial DNA also exists and remains unaltered from mother to child. That
this is used to determine relatedness.
Background (Understand):
● Nucleic acids = molecules of life
● They have the capacity to store information that controls cellular activity and
development of entire organism
● They do this by controlling the synthesis of proteins
● Proteins: make up structure of body + control chemical processes inside cells (enzymes
are proteins)
● Proteins ultimately control structure + functioning of all living organisms
● Two nucleic acids:
- Deoxyribonucleic acid (DNA)
- Ribonucleic acid (RNA)
Who Discovered the Structure of DNA (SAGS):
, ● King’s College, London (early 1950s): Maurice Wilkins and Rosalind Franklin were trying
to work out structure of DNA
● Took experimental approach: looked at X-ray crystallography (diffraction images of DNA)
● At same time at Cavendish Institute (Cambridge University) graduate students Francis
Crick and research fellow James Watson also became interested in determining the
structure of DNA
● They analysed the x-ray data collected by Rosalind Franklin and others
● They built a model out of brass plates and clamps and other bits of laboratory equipment
and realised that nucleic acids are arranged like a twisted ladder (with 2 runners made of
phosphates and sugars and a series of rungs made of pairs of organic compounds
known as bases)
Genetic Replication (unravelling of genetic code) (SAGS):
● Watson and Crick developed ideas about genetic replication in a second article in
Nature, published May 30th 1953
● Pairing of bases (A with T and C with G) showed that ---> given a sequence of bases in
one strand, the other strand was automatically determined
● This meant that when two strands separated, each served as a template for a
complimentary new chain (thus each strand could replicate)
● After ‘double helix’ model, there were still Q’s about how DNA directs the synthesis of
proteins
● 1961: Francis Crick and Sydney Brenner provided genetic proof that a Triplet code was
used in reading genetic material in DNA and transferring the information from nucleus to
cytoplasm via RNA to where proteins are made
● The two showed that in DNA- form is function: double-stranded molecule could both
produce exact copies of itself (replicate) and carry genetic instructions
● Thus the sequence of bases in DNA forms a code by which genetic information can be
stored and transmitted
Who Won The Nobel Prize (understand):
● Rosalind Franklin: only researcher with a degree in chemistry
● Worked alone and suspected (through her x-ray diffractions) that all DNA molecules
were helical in structure but she was reluctant to announce this finding until she had
sufficient evidence
● She died of cancer at 37, before expressing her views
● 1962: Watson, Crick and Wilkins won nobel prize for physiology/medicine (Franklin was
dead)
● Nobel prize only goes to living recipients and can only be shared among 3 winners
● Would she have received the prize if she were alive though? (women in era, oppressed
and not recognised)
, DNA:
The Location of DNA (SAGS):
● Found mainly in the nucleus of a cell where it forms an important part of chromosomes
that make up chromatin network
● Chromatin: chromosomal material made up of DNA, RNA and histone proteins found in
a non-dividing cell
● DNA molecule, coiled so that these long structures can fit inside nucleus (2m of DNA in
every cell)
Extracellular DNA (understand):
● Small amounts of DNA found outside the nucleus in: mitochondria in plants and
animals as well as in chloroplasts in plants
The Structure of DNA (SAGS):
● Shape: long, twisted ladder. Two strands twist to form stable, 3-dimensional double
helix.
What Units Make Up DNA (SAGS):
● DNA molecule: long chain (polymer) made of small units (monomers) i.e: building blocks
called nucleotides. Each nucleotide is made up of a:
❏ Deoxyribose (sugar molecule)
❏ Phosphate molecule (P)
❏ Nitrogenous base which may be:
- Adenine (A)
- Thymine (T)
