Brain Evolution Flashcards
Lecture 4
What is evolution?
Process and change in the genetic coding of a group of organisms from one generation to the next
How does evolution occur?
Natural selection - high survival traits are passed on
What did evolution bring to humans?
Increased brain size
What is Mendelian genetics?
A method to predict genetic inheritance of offspring
Who proposed the theory of evolution and when?
Darwin 1859
Define phenotype
Observable trait
Define genotype
The genetic material constituting the observable trait
Define gene
An inherited factor
Define Alleles
Two genes that control the same feature
Define homozygous
An organism that possess two identical alleles
Define heterozygous
An organism that possesses two different alleles
What are chromosomes?
A threadlike structure found in the nucleus of the cell
How do chromosomes presented?
In matched pairs; each pair contains one allele which determines a given trait
How many chromosomes do humans have
46 (or a pair of 23)
What is the only exception of identical chromosomes?
Sex chromosomes
What are examples of atypical sex chromosomes?
Turner’s syndrome (X0) Klinefelter’s syndrome (XXY) - an extra female chromosome
What does DNA stand for?
Deoxyribonucleic acid
What is DNA?
A double stranded polymer molecule which contains deoxyribose
What does each strand contain?
A sequence of : Adenine, Thymine, Guanine, Cytosine
What is RNA?
Ribonucleic acid
How is RNA different from DNA?
RNA is a single stranded chain of polymers
What are the methods of cell division?
Mitosis, Meiosis protein synthesis, Genetic mutation
How does mitosis take place?
Creation of two identical daughter cells from one parent cell
How does meiosis occur?
Cell division across generations
How does protein synthesis take place?
Has two steps, 1) Transcription - Transfer of genetic material on the DNA to messenger RNA
2) Translation - The code in the messenger RNA is read and transferred RNA in ribosomes which builds polypeptide chains from amino acids
What are genetic mutations?
Changes to the DNA sequences that happens during cell division when the cells make copies of themselves
How do genetic mutations occur?
Can be inherited from a parent or acquired during the life time
What is the most common genetic condition?
Downs syndrome
What causes down syndrome?
Born with an extra copy of chromosome 21
What is down syndrome associated with?
Delay in physical growth, intellectual disability, distinct facial features, poor immune function and increased risk for other conditions
What is Proteus syndrome?
Mutation in the AKT1 kinase in a mosaic state gene in chromosome 10 or 16. It associated with skin, bone and tissue overgrowth
List single gene disorders
Huntingtons disease
What is huntington’s disease?
A neurodegenerative condition which is inherited which mainly effects he coordinated movement and cognitive ability
What is translocation known as?
De la chapelle syndrome (XX)
What is translocation?
Male phenotype with female chromosomes
How can individual with translocation still have the male phenotype?
Role of the Y chromosome in the SRY gene is still included
What is incomplete dominance?
Tay-sachs disease which causes the destruction of nerve cells in the CNS
When is incomplete dominance apparent?
6 months
What are the symptoms of incomplete dominance?
Excessive startle response, losing the ability to crawl, seizures and hearing loss
What is genomic imprinting abnormalities caused by?
Deletion in chromosomes 15 in the 15q11-q13 region
What condition with the branch of genomic imprinting abnormalities?
Angelman syndrome and Prader Willi syndrome
What causes angelman syndrome?
Loss of maternally inherited genes
What are the symptoms of angelman’s syndrome?
Mental retardation, sexual development deficiencies, hyperphagia obesity, sleep disorders, seizures, ataxia and laughter outbursts
What is prader willi syndrome caused by?
Loss of paternally inherited genes
What are the symptoms of Prader Willi syndrome?
Excessive appetite, restricted growth weak muscles, learning difficulties, lack of sexual development and behavioural challenges
What is multiple allele inheritance?
More than two alleles on the chromosome
What are common conditions that arise from multiple allele inheritance?
ABO blood type, Breast cancer, Muscular atrophy and Cystic fibrosis
What conditions are known as the classics?
Schizophrenia, autism and Alzheimer’s
Define Schizophrenia
A mental health condition where individuals where may see, hear or believe things that are not real it is caused by a genetic vulnerability
What genes are implicated in schizophrenia?
It is polygenetic (multiple genes involved) 21 ad 23 chromosome pairs implicated and the DISC- 1 gene
Define Autism
A developmental disability caused by difference in the brain associated with social communication and interaction deficits and restricted or repeated behaviours or interests
What genes are implicated in autism?
Also polygenetic, evidence is still limited
Define Alzheimer’s Disease
A progressive neurodegenerative disease where symptoms gradually become more and more severe
What functions of the brain does Alzheimer’s impair?
Memory in particular
What are the genes identified in association with Alzheimer’s?
APOE-e4 gene identified as a risk gene
How are genetic influences studied in psychology?
Twin studies- Mono vs dizygotic
What is the human genome project?
Began in 1990 as an international project, it aimed to compile a map of 3 million nucleotide bases that comprise the human chromosome
What is the goal of the human genome project?
Link genome variations to disease and develop treatments
What are the limitations of Mendelian genetics?
Does not use modern techniques, protein coded genes make up only 1% of DNA
What is Epigenetics?
Study of all mechanism of inheritance
What is eugenics?
A set of beliefs and practices that in the past aimed to improve the genetic qualities of a human populations, it strived for racial improvement via planned breeding.
