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Neuroscience Year 2 > Genetics > Flashcards

Genetics Flashcards

(56 cards)

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1
Q

What did Mandel do?

A

Studied genetics

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2
Q

What is a dichotomous trait?

A

A trait which occurs in one form or another

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3
Q

What is a true breeding line?

A

Interbred members always produce offspring with the same trait

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4
Q

What is a phenotype?

A

An organisms’ observable traits

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5
Q

What is a genotype?

A

The traits which can be passed onto the offspring via the genetic material

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6
Q

What was Mandellian theory?

A

Two kinds of inherited factors for each dichotomous trait
Each organism possesses two genes for each of its dichotomous traits
One of two kinds of genes dominate
For each trait, each organism randomly inherits one of its father’s alleles and one of its mother’s

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7
Q

What does homozygous mean?

A

Possesses two of the same allele

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8
Q

What does heterozygous mean?

A

Possesses two different alleles for a trait

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9
Q

What is a chromosome?

A

Threadlike structure of the nucleus of each cell

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10
Q

How many pairs of chromosomes does a human have?

A

23

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11
Q

Where are genes located?

A

On chromosomes

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12
Q

Two alleles that control each trait are situated where?

A

At the same locus, one on each chromosome

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13
Q

What are gametes?

A

The sperm and egg

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14
Q

What is meiosis?

A

Process of cell division that produces gametes

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15
Q

What does meiosis produce?

A

Gametes

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16
Q

Process of meiosis

A

Chromosomes divide

One chromosome from each pair goes to each of the two gametes

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17
Q

How many chromosomes do gametes have?

A

23

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18
Q

How many chromosomes do humans have?

A

46 (23 pairs)

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19
Q

What does meiosis account for?

A

Most of the genetic diversity within a species

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20
Q

How does meiosis account for diversity?

A

Crossing over

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21
Q

How does crossing over work?

A

Chromosomes line up in pairs
Cross over one another at random points
Break apart and exchange sections of themselves

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22
Q

Why is crossing over important?

A

Ensures genetic diversity

First means by which geneticists could construct a gene map

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23
Q

What is mitosis?

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A

Cell division of all other cells in the body

24
Q

What is linkage?

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A

Clusters of linked genes
If a gene for one trait is inherited from one parent, there is a higher probability (>0.5) of inheriting genes for other traits in the cluster from the same parent

25
The number of clusters of linked traits is equal to?
The number of pairs of chromosomes
26
4 DNA bases
Adenine Thymine Guanine Cytosine
27
DNA replication
DNA starts to unwind Exposed bases attract complementary loose bases from the fluid of the nucleus When unwinding is complete, two identical double-stranded DNA molecules are created
28
Virtually all sex linked traits are carried on what chromosome?
X
29
If a sex-linked trait is dominant it occurs...
More frequently in females as they have twice the number of X chromosomes
30
If the sex-linked trait is recessive it occurs...
More frequently in males as they only have one X chromosome and so only have to have one recessive allele compared to women's two
31
Example of sex-linked trait
Colour blindness | Rarely occurs in females as it is recessive and the allele is very rare
32
What is a structural gene?
Genes that contain information necessary for the synthesis of a protein
33
What is a protein?
A chain of amino acids
34
What is an operator gene?
Controls a structural gene or a group of structural genes Determines if structural gene initiates protein synthesis And at what rate
35
Operator genes that are regularly on
Are regulated by DNA-binding proteins that turn them up, down or off
36
Operator genes that are regularly off
Are regulated by DNA-binding proteins that turn them on
37
Gene expression transcription
Small section of chromosome that contains structural gene unwinds Unravelled section serves as template for transcription of RNA mRNA moves out of the nucleus and attaches to a ribosome in the cytoplasm
38
Gene expression translation
Ribosome moves along RNA strand and translates genetic code Every 3 bases = codon Codons code for amino acids Amino acids are carried to the ribosome by tRNA Repeats until stop codon reached Completed protein is released into cytoplasm
39
Why is mitochondrial DNA of great interest to scientists?
Mutations have been implicated in many disorders | Mutations seem to occur at a consistent rate and so can be used as an evolutionary clock
40
What is the human genome project?
A map of the sequence of all 3 billion bases that compose human chromosomes
41
How many protein coding genes do humans have
About 25000 (unexpectedly small in relation to our complexity) Mice have about the same Corn have many more
42
What is alternative splicing?
Mechanism by which information stored in the genes of complex species is edited to make it possible for one gene to specify two or more distinct proteins
43
What do small RNAs do?
Control DNA Can turn off genes Control their level of expression Cleave DNA into segments
44
Structural genes constitute how much of the human genome?
<2%
45
What are genes that appear to have been damaged by mutation over evolution called?
Pseudogenes
46
Ontogeny
Development of individuals over their lifespan
47
Phylogeny
Development of species over evolutionary time
48
Phenylketonuria
High levels of phenylpyruvic acid in urine | Pattern of transmission indicates it is transmitted through a single gene mutation
49
What do patients with PKU lack?
Phenyalanine hydroxylase | Converts phenylalanine --> tyrosine
50
Symptoms of PKU
``` Mental retardation Vomiting Seizures Hyperactivity Hyper-irritability Brain damage ```
51
Sensory phase of male songbirds
Several days after hatching Form memories of adult songs they hear Genetically prepared to learn songs of their own species
52
Sensorimotor phase of male songbirds
When juvenile males begin to twitter sub songs | Rambling vocalisations are gradually refined to resemble songs of the adults
53
Neural circuits that control birdsong
Descending motor pathway | Anterior forebrain pathway
54
Descending motor pathway
From high vocal centre on each side | To the syrinx
55
Anterior forebrain pathway
Mediates song learning
56
What is a heritability estimate?
Numerical estimate of the proportion of variability that occurred in a particular trait in a particular study as a result of the genetic variation in that study

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