Nutrition and Genetics Flashcards
What is DNA?
Deoxyribonucleic acid (DNA) contains the instructions for the development, growth, function and reproduction of cells and therefore entire organisms
Who discovered DNA?
Watson & Crick
What are the 4 base pairs?
What is the other base pair seen in RNA (replaces thymine)?
A - Adenine
T - Thymine
G - Guanine
C - Cytosine
U - Uracil
What is a genome?
The total of all genes
How many base pairs in the human body?
approx. 3 billion
When did the human genome start and end?
1990-2013 (10 years ahead of schedule
How many pairs of chromosomes does a human possess?
23 pairs
(46 individual)
Which chromosome pairs are the autosomes?
pairs 1-22
Which chromosome pairs are the sex chromosomes?
pair 23
What is the chromosome sequence for males and females?
Female - XX
Male - XY
Which pair of chromosomes are affected to cause down syndrome? How?
pair 21 extra chromosome (3 total)
What is a gene?
basic unit of hereditary, codes for a specific trait
What is a allele?
two or more versions of a gene
What is the difference between a homozygous and heterozygous gene?
Homozygous: You inherit the same version of the gene from each parent, so you have two matching genes.
Heterozygous: You inherit a different version of a gene from each parent. They do not match.
What is the difference between genotype and phenotype?
Genotype - Genetic make-up on an individual -not always an observable characteristic
Phenotype - The observable characteristics of an individual resulting from the genotype
Genes can vary in 3 differing locations of DNA. Where?
- Single nucleotide - (base change, insertion, deletion)
- Groups of nucleotides (repeats)
- Whole chromosome (insert, deletion, rearranging)
What gene has had associations with obesity?
FTO gene
What are the structural differences between DNA and RNA?
DNA -
Deoxyribose sugar
double stranded
thymine base
RNA -
Ribose sugar
single stranded
uracil base
comprises mRNA, tRNA, rRNA
What is gene expression?
The conversion of information encoded in a gene > mRNA > protein
What determines the structure of a protein?
DNA base codes
What is a sequence of 3 base codes called?
A codon
Are all amino acids coded for using only 1 codon?
No, some amino acids can have multiple codons.
E.g. proline can be coded by codons; CCG, CCU, CCC OR CCA
What organelles are the site of protein synthesis? Where does this occur?
Ribosomes
In the nucleus of the cell
What is transcription? (protein synthesis)
The process of making an RNA copy of a gene sequence, results in a copy called mRNA
What is the enzyme responsible for the lining up of base pairs during transcription?
RNA polymerase
What are the steps of translation? (protein synthesis)
- consists of 3 steps: initiation, elongation & termination
- mRNA produce by transcription attaches to ribosome , initiated by start codon
- tRNA molecules transport specific amino acids to the ribosome
- each mRNA codon codes for a specific amino acid
- elongation as amino acid chain is built
- continues until a stop codon is reached
- protein built
Why is it important to study genetics in nutrition?
Because what we eat can directly affect our gene expression
What are the definitions of these key terms?;
- gene
- locus
- genome
- somatic cells
- gamete
- chromosome
- chromatid
- centromere
- gene: basic unit of hereditary, codes for specific traits
- locus: specific location of a gene or chromosome
- genome: the total endowment of DNA of an organism
- somatic cells: all body cells except reproductive cells
- gamete: reproductive cells (sperm & eggs)
- chromosome: composed of DNA and protein, encompass the DNA in cells
- chromatid: one of two duplicated chromosomes connected at the centromere
- centromere: region of a chromosome where microtubules attach during meiosis and mitosis
What are the 3 phases of interphase? What happens during each phase?
G1 - cell growth and preparation for replication
S - DNA replication and chromatid duplication
G2 - more growth
Prior to mitosis, what phase must take place?
Interphase (G1, S, G2)
Chromosomes cannot be seen individually in the cell so they are called what?
Chromatin (dispersed chromosomes)
Are centromeres located inside or outside the nucleus? What do they consist?
Outside
2 centrioles
What are the 4 stages of mitosis?
Prophase > Metaphase > Anaphase > Telophase
What happens during prophase?
- chromosomes become more visible (condensed)
- mitotic spindle forms between centrioles
- a pair of sister chromatids are observed
What happens during metaphase?
- centromeres move to opposite poles of the cell
- mitotic spindles attach to chromosome centromeres
- chromosomes become arranged on a plane (metaphase plate)
What happens during anaphase?
- sister chromatids separate due to the pulling of the mitotic spindles
- daughter chromosomes are formed and move to opposite poles of the cell
- a complete set of chromosomes are assembled at each pole of the cell
What happens during telophase?
- chromosome sets are assembled at opposite poles
- nuclear envelope reforms
- cytokinesis begins (division of cytoplasm)
- chromosomes unfold back into chromatin (uncondense)
Define mitosis and meiosis?
Mitosis - Produces daughter cells with identical number of chromosomes as the parent cells
Meiosis - The division process in sexually reproducing eukaryotes resulting in cells with one-half the number of chromsomes of the original parent cell
What is the difference between haploid and diploid cells?
Diploid cells have2 full sets of chromosomes.
Haploid cell have one half a set of chromosomes (1/2 diploid)
Meiosis occurs in how many successive nuclear division? What are they?
Two
Meiosis I and Meiosis II
What are the stages of meiosis I and meiosis II?
Both are:
- premeiotic interphase
- prophase I & II
- metaphase I & II
- anaphase I & II
- telophase I & II
What happens in each step if meiosis I?
premeiotic interphase - chromosomes duplicate. outside the nucleus are two centromeres with a pair of centrioles
prophase I - chromosomes become visible, crossing over occurs which leads to genetic variation. Nucleolus disappears, meiotic spindle forms, nuclear envelope disappears
metaphase I - the pairs of chromosomes (bivalents) become arranged on the metaphase plate and attach to meiotic spindle
anaphase I - the two chromsomes in each bivalent seperate and migrate towards opposite poles
telophase I - the chromosome pairs are at the poles and nuclear envelopes form around them. Cytokinesis occurs to produce two cells
What happens during meiosis II?
PMAT - similair to mitosis
What are the two steps of protein synthesis?
Transcription and Translation
What cells does mitosis and meiosis result in?
Mitosis - 2 identical diploid (2n) somatic daughter cells
Meiosis - 4 haploid (n) gamete cells that are genetically unique
What is epigenetics?
The study of changes in an organism cause by modification of gene expression not involving changes to the genetic code itself
What is nutrigenomics?
The study of the interaction of nutrition and genes, with particular interest in the prevention/treatment of disease.
Diet alters expression of genes (hormones, chemicals)
Can affect genes expression direcly or indirectly
What is nutrigenetics?
The study of how genetic variation affects the respose to different nutrient intakes
What is a polymorphism?
A relatively common genetic variation where one or more morphs are seen of the same DNA sequence
What is the reduced foetal grwoth hypothesis?
This hypothesis states that reduced foetal growth is strongly associated with many chronic conditions in later life.
Occurs due to genetic adaptations made by the foetus in a nutritionally inadequate environment
