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PSYC20008 - Theme 3: Biology > W9L2 - Human Genetics 1 > Flashcards

W9L2 - Human Genetics 1 Flashcards

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1
Q

What are the phenotypes of Down’s Syndrome

A

Distinctive physical characteristics

  • Sloping forehead
  • Protruding tongue
  • Short stubby limbs
  • Slightly flattened nose
  • May have congenital eye, ear, heart deficits

These are examples of phenotypes

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2
Q

Define Phenotype

A

Observable properties of an organism produced by:

(a) genotype; and
(b) environmental influences

(Examples: hair colour, EF abilites, height, conditions)

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3
Q

How many cells are there in a human body. And how many chromosomes are in a human cell.

A
  • Human body contains 100 trillion cells.
  • There is a nucleus within each human cell
  • And each nucleus contains 46 chromones, arranged in 23 pairs
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4
Q

How are chromosomes arranged. What is within the chromosones?

A
  • 46 chromsomes arranged in 23 pairs
  • (one set from mother and one set from father)
  • Autosomes: 1-22
  • Sex chromosome: 23
    • The chromosomes are filled up with tightly coiled strandes of DNA
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5
Q

What are gamates

A

Sex cells - Sperm from male and ova from female

  • Gamates each contain only 23 chromosomes
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6
Q

What do chromosomes carry. What are chromosomes-pairs?

A

Genetic information, arranged in a linear sequence

  • Each chromosome carries genes of the same type
  • Chromosome-pairs match in size and functions they serve
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7
Q

What are chromosomes made up of?

A

Chromosomes are made up of chromatin

  • Chromatin constitutes nucleic acids (DNA and RNA) and proteins
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8
Q

When are chromosomes visible?

A

Only during cell division process (meitosis and meiosis)

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9
Q

What is a karyotype

A
  • Description of chromosonal content in a cell, which includes
  • number. of chromosomes and description of sex chromosomes
    • Autosomes are numbered 1 to 22
    • Sex chromosomes are either X or Y
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10
Q

What happens in XY + extra 21 (Total 47)

A

Male’s down syndrome

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11
Q

What happens in XX + extra 21 (Total 47)

A

Female’s Down

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12
Q

What happens in 45, X

A

Turner’s Syndrome (Females only)

  • Timmy turner is a female!
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13
Q

What happens in 47, XXY

A

Klinefelter’s Syndrome (Males only)

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14
Q

How does XXY affect development. Write down 3 ways.

A

Kleinfelter’s Syndrome

Physical development

  • Lagging
  • Weak muscles and reduced strength

Language Development

  • Between 25-85% of XXY males have langauge difficulties

Social development

  • XXY males tend to be more quiet and undemanding compared to XY males
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15
Q

Define nucleotide

A

Building blocks of DNA/RNA

Base + Sugar + Phosphate Group

  • Sequence of DNA is described by the order of bases (ATGC) in a 5” prime end to 3” prime end
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16
Q

What is the sequence of DNA. How is it related to genes?

A

Order of bases in a 5’ to 3’ direction

DNA

  • Double stranded structure that consist of 2 nucleotides held together by hydrogen bonds between the bases in opposing strands
  • DNA molecules are organised into stretches of sequence called genes
17
Q

When can a gene influence development

A

It can only influence when it is turned on and expressed

i.e. it must be transribed

18
Q

What is a locus

A

Sequence of DNA on specific location in chromosome

19
Q

How is RNA related to DNA

A

RNA converts (transcribe and translate) the genetic information contained within DNA to a format used to build proteins

20
Q

How does mRNA code for each amino acid

A

Using codons: Groups of three bases of mRNA

  • There are 64 possible codons but there are only 20 different amino acids (which codes for everything)
21
Q

What are proteins (in terms of genes). How many are there

A
  • Proteins are the end product of gene expression
  • 20 different kinds (though there are 64 possible codons)
22
Q

What are 4 main types of mutation

A
  1. Base substitution
  2. Deletions of DNA
  3. Insertion of DNA
  4. Whole/partial chromosonal abnormalities
23
Q

What are alleles. How many

A
  • One of two or more variations or a gene
  • About one-third of humans genes are alleles
    • The allele of a given gene influences same trait or characteristic, and fiferent alleles results in different characteristics
24
Q

What is the SNP

A

Variation in one base pair

25
Q

What are forms of a gene that is expressed/not expressed

A

Dominant Allele:

  • Form of gene expressed if present

Recessive Allele:

  • Not expressed if dominant allele is present
26
Q

Are traits governeed by more than one gene? What is this called?

A

Polygenic Inheritance

Yes most traist are governed by more than one gene

27
Q

What is the difference between mitosis and meiosis

A

Mitosis

  • Each daughter cell with 46 chromosomes
  • Cell separates the chromosomes into two identical sets, in two separate nuclei

Meiosis:

  • Each daughter cell with 23 chromosomes
  • The DNA is replicated, recombined, and the cell divides twice
  • Gamates
28
Q

What is mitosis

A

Mitosis

  • Cells separate chromosomes in nucleus to 2 identical sets in 2 separate nucleii
  • 2 Daughter Cells which are genetically identical to each other and their parent cell
29
Q

What is meiosis

A

Meiosis

  • Necessary for sexual reproduction
  • Produces gametes (X/Y)
  • DNA is replicated, recombined, and cell divides twice
  • Results in 4 daughter cells
30
Q

What are genetic mutations

A
  • Process of change in sequence of DNA
  • They are the source of genetic variation and basis for natural selection
    • Base subsittutions
    • Deletions of DNA
    • Insertion of DNA
    • Whole or partial chromosonal abnormalities

PSYC20008 - Theme 3: Biology (1 decks)

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