Genes, DNA, and Behaviour Flashcards
Lecture 2
where is DNA located
the nucleus of cells
which cells do not have a nucleus with DNA
- red blood cells
- hair
- cornified skin
- cornified nails
why do red blood cells not have nucleus with dna
destroyed during maturation
what percentage of dna codes for proteins
1%
what does the remaining 99% of DNA do
regulate gene activity and transcription
describe the DNA to proteins process
DNA -> transcription -> mRNA -> translation -> amino acids -> proteins
what is chromatin made up of
DNA and proteins
how it dna made dense and more manageable in the nucleus
wraps around proteins
does more chromosomes = more complexity
no,
bananas = 11 pairs, fruit flies = 4 pairs
what is a gene
basic physical; and functional unit of heredity.
it is a length of DNA
what is an allele
versions of the same gene, inherited from each parent
what bonds the base pairs
hydrogen bonds
what is a codon
triplet of bases which code for an amino acid
is genetic code universal
yes - its the same for humans, bacteria, and everything in-between
how many possible codons code for 20 amino acids
64 (including start and stop)
61 for just the amino acids
what is a genotype
an organisms complete set of DNa
what is a phonetype
characteristics of the organism
what is a gamete
reproductive sex cell
what is menders law
- segregation - alleles separate during gamete formation
- independent assortment - genes segregate independently during gamete formation (e.g. we are like our siblings and parents, but not identical)
- dominance - some alleles are dominant and some are recessive. the effect of the dominant allele will be displayed and the recessive will be masked
how many pairs of chromosomes do humans have
23, from each parent
how are gametes produced
meiosis
what is meiosis
how sperm and eggs are formed.
what may errors in meiosis cause
miscarriage and developmental disorders
are daughter cells identical to parent cells
no - due to shuffling of genes between chromosomes
what is interphase
chromosomes duplicating
what is crossing over
random shuffling of genes, forming daughter cells
What does GWAS stand for?
Genome Wide Association Studies
How many publications are related to GWAS?
Almost 4000 publications
What are the associations found in GWAS?
138,000 variant-trait associations
What type of genetic disorder is monosomy?
Missing X chromosome
What is trisomy 21 also known as?
Down’s Syndrome
What are some health issues associated with Down’s Syndrome?
- Intellectual disability
- Heart issues
- Respiratory issues
- Digestive issues
What characterizes Turner Syndrome?
Physical characteristics like webbed neck and heart, kidney issues
What is aneuploidy?
Too many or too few chromosomes
What causes single gene disorders?
Mutations to a single gene
What are multifactorial disorders caused by?
Mutations to multiple genes combined with environmental influence
What type of inheritance involves one copy of the gene causing the condition in males?
X-linked recessive inheritance
Give examples of conditions inherited through X-linked recessive inheritance.
- Haemophilia
- Red-green colour blindness
What is required for autosomal recessive inheritance to cause a condition?
Two copies of the gene
Provide examples of conditions inherited through autosomal recessive inheritance.
- Cystic fibrosis
- Sickle cell disease
What is required for autosomal dominant inheritance to cause a condition?
One copy of the gene
Give examples of conditions inherited through autosomal dominant inheritance.
- Huntington disease
- Marfan syndrome
What happens during interphase?
Chromosomes duplicate
What is crossing over?
Random shuffling of genes
What is the process called through which sperm and eggs are formed?
Meiosis
What is the genetic makeup of humans in terms of chromosome pairs?
23 pairs of chromosomes
What does the CFTR gene code for?
A protein in the membrane of cells that make mucus
What is the primary focus of GWAS?
Correlation between differences in (Single nucleotide polymorphisms) SNPs and presence of traits
What are Single Nucleotide Polymorphisms (SNPs)?
simple genetic variations at a single base pair (nucleotide)
What is heritability?
Degree of variation in a phenotypic trait due to genetics
What is the aim of twin studies?
Establish the proportion of a trait due to genetics, shared environment, and non-shared environment
What does a heritability of 30% indicate?
30% of the variation in that trait is caused by genetics
What is the significance of the gene MAOA-L in relation to childhood adversity?
It is linked to violent, antisocial behaviour
Define multifactorial disorders.
Conditions influenced by many different genes and multiple environmental factors
What are Mendel’s laws of inheritance?
- Segregation: Alleles separate during gamete formation
- Independent assortment: Different genes segregate independently
- Dominance: Some alleles are dominant and some are recessive
What is a genotype?
An organism’s complete set of DNA
What is a phenotype?
The characteristics of the organism
What does epigenetics involve?
Modifications to DNA that do not change the DNA sequence but can affect gene activity
What percentage of DNA codes for proteins?
1%
What is the function of the 99% of DNA that does not code for proteins?
Regulates gene activity and switches genes on and off
Where is DNA primarily located in the cell?
In the nucleus
What is the structure of DNA?
Double helix composed of a sugar-phosphate backbone and nitrogenous bases
What does the term ‘allele’ refer to?
Versions of the same gene inherited from each parent
What is the role of proteins coded by genes?
They perform various functions such as enzymes, hormones, and tissue formation
How many chromosomes does a single sperm or egg cell contain?
23
Down syndrome is caused by:
a trisomy of chromosome 21
The observable characteristics of an individual are referred to as one’s:
phenotype
In a strand of DNA, adenine can only bond with which base?
thymine
In addition to natural selection, Darwin proposed that species could evolve through ________ selection.
sexual selection
what is a nucleotide
a single unit of DNA (base+sugar+phosphate)
if dna sequence is A-T-G-C-A, and C was changed for a SNP, what would SNP version look like
A-T-G-(T)-A
what are the two phases of meiosis called
- reduction division
- separation of sister chromatids
what happens during reduction division (meiosis)
goes from 46 chromosomes to 23.
what is the order of the phases in each phase of meiosis
- prophase
- metaphase
- anaphase
- telophase + cytokinesis
out of 64 possible codons, how many stop and start codons
1 start codon
3 stop codons
what is the start codon
AUG
what does the start codon also code for
methionine
what are the stop codons
UAA, UAG, UGA
