Topic 1 - Human Variation & Diversity Flashcards
What is biological determinism?
The view that every characteristic of an organism’s functioning is determined by the genes it has inherited
What is the definition of the human genome?
The total genetic material within a cell
What is human genomics?
The combined application of medical technologies and genetics to diagnose, prevent and treat disease
What is a genotype?
The entire complement of genes of an individual, or the specific alleles of a single gene
What is an allele?
A known variation of a particular gene. Every individual carries two alleles of each gene, one from each parent
What is a phenotype?
The characteristics of an individual (be it anatomical, physiological or biochemical) which are determined by both genetic and environmental factors
What is the definition of a recessive disorder?
A disease in which two copies of a defective gene must be inherited in order for the disease to be expressed
In 2014, how many people did the WHO estimate to be overweight?
More than 1.9 billion adults (600 million of which were obese) and 41 million children
What problems can excessive visceral fat cause?
Increases the risk of diabetes, heart attacks and strokes
What is the thrifty genotype hypothesis?
A hypothesis which suggests that members of certain human populations have a genotype which promotes fat storage, predisposing them to obesity and type 2 diabetes when eating high-energy diets
What is the formula we can use to understand phenotypes?
Genotype + environment = phenotype
In 2015, what were the three leading causes of deaths in high-income countries?
- Ischaemic heart disease
- Stroke
- Alzheimer’s disease/other dementias
What is a single nucleotide polymorphism?
A variation in a genetic sequence which only affects one of the basic blocks (A, C, G, T) in a segment of a DNA molecule, and that occurs in more than 1% of the population
How much of the DNA sequence is the same for every human?
99.9%
What are mRNA codons?
A 3 base pair long part of the mRNA which codes for a specific amino acid in the ribosomes of a cell
What do amino acids create?
Proteins
What is a characteristic of a dominant genetic disorder?
That there is at least one affected individual in every generation
What is a characteristic of a recessive genetic disorder?
It often misses generations within a family pedigree
Is the DNA molecule stable or fragile?
Very stable
What are DNA base triplets called?
Codons
What does mRNA do?
Acts as an intermediary in the conversion of DNA codons into amino acids
In the human genome, roughly how many genes code for proteins?
25,000
What are the three properties of DNA?
- It is relatively stable
- Its structure is easily duplicated or replicated
- It carries a store of vital information which is used in the cell to produce proteins
What are the building blocks that each strand of DNA is made from?
Nucleotides
What is a nucleotide?
A building block of DNA consisting of 3 parts:
- Phosphate
- A sugar (ribose/deoxyribose)
- A base
What is a base?
One of the 3 components of a nucleotide
What are the four bases in DNA?
- Adenine
- Cytosine
- Guanine
- Thymine
In RNA, what is the base thymine replaced with?
Uracil
In each strand of DNA, how are the components joined to each other?
The phosphate of one nucleotide is joined to the sugar of another nucleotide
Is DNA found in plants or animals?
Both
What are the rules for base pairing in DNA?
- T pairs only with A
* C pairs only with G
What are the pairs of bases in DNA known as?
Complementary base pairs
What does “complementary base pair” actually mean in real-world terms?
The order of the bases on one strand of DNA is complementary to the order of bases on the second strand of DNA
What is DNA polymerase?
An enzyme which catalises the synthesis of DNA molecules
What is meant by semi-conservative (DNA) replication?
In each new DNA double helix, one of the two original strands is conserved (unchanged) from the original parent molecule
Roughly how many base pairs of DNA does each human cell contain?
3 000 000 000 (billion)
What are the functions of proteins?
- Contractility, eg muscles
- Shape or structure of individual cells
- Messengers - released from one part of the body and affecting the activity of cells in another part of the body
- Receptors - detecting those messages
- Catalysts - enzymes, which speed up chemical reactions
What are amino acids?
Building blocks of polypeptides and proteins
How many naturally occurring amino acids are there?
20
What do all amino acids consist of?
An amine group and a carboxyl group, both attached to a central atom
What is a peptide?
Short strings of amino acids
What are polypeptides?
A single chain of many amino acids joined together
What is the primary structure of a protein?
A protein is a linear sequence of amino acids
What is the one gene-one protein hypothesis?
The hypothesis that each gene codes for a specific protein
What is the difference between RNA and DNA?
RNA is single-stranded
The individual RNA nucleotides contain ribose sugar instead of deoxyribose sugar
Thymine is replaced with Uracil
What is DNA transcription?
The synthesis of an RNA molecule using DNA as the template
What is DNA translation?
The process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis
What is RNA in regards to the process of DNA transcription?
An intermediary in the flow of information from DNA to protein
What are RNA’s four bases?
- Adenine
- Guanine
- Cytosine
- Uracil
What is mRNA (messenger RNA)?
A single-stranded molecule of RNA which is produced by the transcription of DNA
What information does mRNA carry?
The code for the amino acid sequence of a particular protein
What is tRNA (transfer RNA)?
Small RNA molecules which are involved in protein synthesis, each carrying a particular amino acid
What is an anticodon?
A triplet of bases in tRNA which plays an important role in the translation of mRNA at the ribosome and the synthesis of the primary structure of protein
What is a codon?
A triplet of mRNA nucleotides whcih correspond to a specific amino acid, or stop signal in the genetic code
What is the function of codons in a protein-coding mRNA molecule?
To determine the amino acid sequence of the polypeptide
What is an anticodon composed of?
Three bases which correspond to a complementary codon in mRNA which codes for a specific amino acid
What is the sequence of events in (DNA) translation?
mRNA -> tRNA + amino acid -> protein
Where is mRNA made?
In the cell nucleus
Where does (DNA) translation occur?
Outside of the nucleus on ribosomes
What are ribosomes?
Particles composed of RNA and protein
What is the function of ribosomes?
They are the sites of protein synthesis in the cell
What structure in a cell are ribosomes usually attached to?
The endoplasmic reticulum
