Genetics & Evolution for Psychology > Problem 1 > Flashcards

Problem 1 Flashcards

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1
Q

Phenotype

A

Refers to the observable characteristics of an individual ex.: size, shape, color

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2
Q

Genotype

A

Refers to the set of genetic variants that an individual bears

–> plays a crucial role in giving rise to the phenotype

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3
Q

Genes

A

Refers to a DNA sequence coding for a protein

–> consist of alternations of axons + introns

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4
Q

Prokaryotes

A

Are organisms whose cells lack a distinct nucleus

ex.: bacteria

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5
Q

Eukaryote

A

Refers to an organism whose cells have a distinct nucleus

–> all animals + plants

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6
Q

Proteins

A

Are large molecules made up of long chains of amino acids

–> give cells their shape and make up about 12-18% of total body weight in humans

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7
Q

Amino acids

A

Are the molecular building blocks of proteins

–> its sequence along the chain determines what the properties of the protein will be

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8
Q

What where the 3 phases in genetics ?

A
  1. Classical genetics

–> discovering the concept of the gene (Mendel)

  1. Molecular genetics

–> discovery of the DNA (Watson + Crick)

  1. Genomics

–> ability to read genes

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9
Q

Principles of classical genetics

A
  1. Certain genes are based from parents to offspring
  2. Genes often come in alternate forms, called alleles
  3. Individuals have two copies of each gene, with one copy coming from each parent
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10
Q

Diploid

A

Refers to a cell/organism containing 2 sets of genes, one from each parent

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11
Q

Haploid

A

Refers to a cell/organism containing only one set of genes

–> in humans, only sperm + egg cells are haploid

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12
Q

Classical genetics established that genes have 2 functions.

Which are they ?

A
  1. Genotype influences the PHENOTYPE
    * –> function a*
  2. Genes REPLICATE themselves to produce new cells
    * –> function b*
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13
Q

Central dogma

A

Refers to the idea that changes in DNA sequences can lead to changes in proteins, but changes in proteins cannot change the sequence

–> the flow of information is one way

ex.: muscles that are built during a lifetime are not passed down to the next generation

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14
Q

Somatic cells

A

Refer to the cells in the body other than gametes

–> are only capable of function a (making more phenotype) by engaging in mitosis

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15
Q

Germ cells/ Gametes

A

Refer to sperm + egg cells

–> are only capable of function b (making more genotype) by engaging in meiosis

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16
Q

Mitosis

A

Refers to a process whereby cells split into genetically identical copies of themselves

–> 2n to 2n

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17
Q

Meiosis

A

Refers to a special cell division process that produces a haploid gamete from a diploid cell

  1. recombination occurs here
  2. 2n to 1n
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18
Q

Chromosomes

A

Consists of DNA wound around proteins called histones

  1. come in homologous pairs, one from each parent
  2. 23 pairs
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19
Q

Desoxyribonuclein acid (DNA)

A

Is a long chain molecule/poymer consisting of 2 strands bound to + twisted around each other in a double helix

  1. each strand is made up of a backbone of sugars + phosphates
  2. along each backbone are strung the bases
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20
Q

Which are the 4 Nitrogenous bases? How can you differentiate them ? Which bases binds to which (Basepairing) ?

A
  1. Adenine, Guanine, Cytosine, Thymine
  2. Adenine + Guanine are PURINBASES, Cytosine + Thymine are PYRIMIDINEBASES
  3. Adenin + Thymin, Cytosin + Guanin
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21
Q

Hydrogen bonds

A

Refer to the bonds between the 2 strands

  1. AT have 2 bonds whereas GC have 3, making them slightly stronger
  2. are weak and can be easily split apart
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22
Q

Process of Transcription

A
  1. RNA Polymerase binds to Promotor + unzips double helix
  2. RNA is synthesized by copying the leading strand

–> done by Polymerase

  1. When the Polymerase meets a terminator, copying ends + RNA separates from the DNA to become mRNA
  2. Introns are cut out of the mRNA in a process of splicing
  3. mRNA moves to Ribosomes
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23
Q

Process of Translation

A
  1. Ribosome is the site of translation
  2. The initiation codon (AUG) methionine signals the start for translation
  3. Termination codons signal the end
  4. tRNA consists of an amino acid at its top + the anticodon at its bottom, always binding to its component at the mRNA
  5. the tRNAs bind together their subsequent amino acids into a polypeptide chain

–> RESULT: Protein

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24
Q

Codons

A

Refer to triplets of bases from the mRNA, which stand for one particular amino acid

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25
What is the Genetic code ?
Its the ***mapping from particular codons*** in the mRNA to particular ***amino acids*** in the assembled protein ex.: AUG coding for Methionine
26
What are the properties of the Genetic code ?
1. **Redundancy** --\> several triplets may code for one amino acid, so errors made in reading the 3rd base may often make no difference to the amino acid 2. **Robust against coding errors** 3. **Property of good design**
27
Exons
Refer to stretches of codons that are translated into the protein --\> genes that will be **ex**pressed
28
Introns
Refer to **non coding sequences in**serted within the gene --\> are transcribed, but then deleted from the mRNA, thus ***not translated***
29
Process of Replication
1. ***Helicase*** cuts open the Hydrogen bonds between the bases --\> develops Leading + Lagging strand 2. RNA primase synthesizes a ***Primer*** which binds to the 5' end of the Leading strand 3. ***RNA polymerase*** can now match the matching nucleotides in 5'-3' direction 4. On the ***lagging strand*** the RNA primase has to synthesize ***new primers*** over and over again so the RNA polymerase can work in 5'-3' direction 5. RNA fragments on the lagging strand are called ***okazaki fragments*** and are replaced by DNA nucleotides with help from the DNA polymerase 6. ***DNA ligase*** connects the former okazaki fragments with the rest of the DNA
30
Pseudogenes
Genes that have ceased to be translated
31
Transposable elements
Have the ability to copy themselves into different parts of the genome as evolution proceeds --\> multiple near identical copies of particular sequences of bases
32
33
Microsatellites (Intron)
Refer to a simple sequence repeats with a short repeated motif, generally of one to six base pairs --\> **shorter**
34
Minisatellites (Intron)
Refers to a simple sequence repeat with a repeated motif of a dozen to a few dozen base pairs --\> longer, therefore prone to mutations
35
Evolvability
Refers to the genomes ability to **generate novel phenotypes** --\> evolvability is enhanced by the presence of repetitive DNA
36
Polyploidy
An organism having more than 2 copies of the genome
37
For what reasons, do individuals have different genotypes from each other ?
1. Sexual reproduction 2. Mutation
38
Why do Gamete cells only have one set of chromosomes ?
The gamete cell has to receive **only half of the set of genetic material** of the progenitor cell from which it is created
39
Recombination
Refers to the event during meiosis that results in DNA being exchanged between the two copies of a chromosome --\> crossover
40
Linkage
When 2 alleles have the tendency to be inherited together, they are said to be linked --\> can be disrupted by recombination
41
Why does linkage arise ?
Because the 2 genetic loci are on the same chromosome --\> the **closer their physical positions**, the tighter the linkage
42
Mutation
Refers to any change in the DNA sequence, leading to considerable ***Genetic variation*** between individuals of the same species --\> occurs during meiosis + mitosis
43
Single base substitutions
Are a type of mutation where ***one base pair is substituted*** for another e.g.: transversions + transitions
44
Transition (Single base substitution)
Changes between similar pairs of bases/ Intrachange of purine and pyrimidine bases --\> C + T or A + G
45
Transversion (Single base substitution)
Interchange of purine for pyrimidine bases --\> C + G or T + A
46
Simple sequence repeat expansion + contractions
Are a type of mutation where ***an extra copy of the repeat motif is either added or lost*** --\> occurs more often than single base substitutions ex.: Huntingtons
47
Transposable element insertions
Are a type of mutation where a transposable element is copied from one part of the genome to another
48
Segmental duplications
Are a type of mutation where a chunk of sequence ***makes an extra copy of itself during replication*** --\> happens often but not necessarily adjacent to the original copy
49
Why are segmental duplications said to be significant in evolutionary change ?
1. One would have one copy sufficient to perform the ***original function*** 2. The second copy can then acquire new mutations that may ***bring in new functions*** without the organism being functionally impaired --\> evolution selection might otherwise get stuck on primary functions
50
Gene families
Refer to multiple genes descended from a **common ancestor** by duplication events
51
Whole genome duplication
Is a type of mutation where the entire genome is duplicated 1. accounts for the polyploidy in the world 2. very rare
52
Locus
Refers to a particular site on the genome
53
Polymorphism
Refers to the presence of genetic variation within a population, upon which natural selection can operate --\> type of mutatuin
54
Which types of mutations are there ?
1. Single base substitutions a) Transition b) Transversion 2. Simple sequence repeat expansion + contractions 3. Transposable elements insertions 4. Segmental duplications 5. Whole genome duplication 6. Single base insertion vs deletion
55
Why do most polymorphisms have **no** phenotypic effect ?
1. Much of it occurs in ***non coding DNA*** 2. Small polymorphisms often make ***no difference*** in the amino acid due to ***redundancy*** of genetic code 3. Even if another amino acid is created, it will have fairly similar properties --\> ***functioning of the protein is not affected***
56
Why are most mutations harmful ?
1. Mutation is **undirected** --\> the effects of mutations are unrelated to the physiological needs + functions of the phenotype 2. The phenotype is a **well functioning system**, so modification is more likely to make it work less well ex. : ripping out a random wire out of a computer --\> will make it most likely work less well
57
Association studies
Are studies were one establishes 2 samples of individuals from the population: those with the phenotypic characteristic of interest and those without it --\> they are then genotyped to ***test for differences in allele frequencies***
58
Single base insertion
Insertions are mutations in which ***extra base pairs are inserted/added*** into a new place in the DNA --\> frameshift mutation
59
Single base deletion
Deletions are mutations in which a ***section of DNA is lost, or deleted.*** --\> frameshift mutation
60
Synonymous mutations
Refer to a mutation that ***_does not_ alter the amino acid sequence of a protein*** --\> due to the **redundancy** of the genetic code these changes usually occur in the 3rd position of a codon
61
Nonsynonymous mutations
Refers to a mutation that ***_alters_ the amino acid sequence of a protein***
62
Epigenetics
Is a way of regulating gene expression 1. meaning how many copies of an RNA molecule are made 2. expression is dependent on the environment
63
**Methylation** (Epigenetic factor) Methylated regulator vs De-methylated regulator
1. Methylated regulator **represses** gene expression 2. De-Methylated regulator **enhances** gene expression
64
Acetylation (Epigenetic factor)
1. Acetylated regulator makes **DNA accessible** (gene active) 2. De-Acetylated regulator makes **DNA inaccessible** (gene inactive)
65
Pleiotropy
Occurs when ***one gene has multiple effects*** on unrelated phenotypic traits --\> adds to mendels model
66
Polygenic trait
Occurs when ***many genes contribute to a single effect*** --\> adds to mendels model
Genetics & Evolution for Psychology
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