Human genetics: L18 Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

what is a phenotype?

A

physical characteristics:

observable properties of an organism produced by the genotype and environmental influences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

example of a phenotype for someone with down’s syndrome

A
  • sloping forehead
  • protruding tongue
  • short limbs
  • flattened nose
  • almond eyes
  • congenital eye, ear and heart defects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

other examples of phenotype

A
  • hair colour
  • executive function abilities
  • short/tall
  • lung capacity
  • psychiatric condition
  • skin tone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

genetic structures

  1. human body has … cells
  2. there is a … inside each cell (except red blood)
  3. each nucleus has … chromosomes
  4. one chromosome from every pair is from ….
  5. chromosomes are filled with ….
  6. … are segments of DNA that contain …
A
  1. 100 trillion
  2. nucleus
  3. 46
  4. each parent
  5. tightly coiled strands of DNA
  6. genes, contain instructions to make proteins = building blocks of life
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q
  • define Gametes
  • each contain how many chromosomes?
  • X/Y =
  • X/X =
A

sex cells - sperm from male, ova from female

  • 23
  • X/Y = male
  • X/X = female
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

each chromosome pair.. (2)

A
  • carries genes of the same type

- match in size and function they serve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

chromosome

  1. information is arranged in …
  2. chromosomes are made up of … which is made up of ….
  3. chromosomes are only visible during…
A
  1. linear sequence
  2. chromatin. Chromatin constitutes nucleic acids (DNA & RNA) & proteins
  3. cell division processes, called mitosis and meiosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

define karyotype

A

chromosomal content of a cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the autosomes?

A

non sex chromosomes (numbered 1-22)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

variations in karyotype:

  1. 46, XY
  2. 46, XX
  3. 47, XY + 21
  4. 47, XX + 21
  5. 45, X
  6. 47, XXY
A
  1. Male
  2. Female
  3. male down’s syndrome
  4. female down’s syndrome
  5. Turner’s syndrome
  6. Klinefelter’s syndrome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is Klinefelter’s syndrome?

  1. physical development
  2. language development
  3. social development
A
  1. weak muscles/reduced strength
  2. 25-85% have language difficulties
  3. XXY males tend to be more quiet and undemanding than XY males
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

which DNA always bind together? 2 pairs

  1. adenine and
  2. guanine and
A
  1. thymine

2. cytosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

sequence of DNA is described by the order of the bases in a what direction?

A

5’ to 3’ direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

humans have … bases

A

3.3 x 109

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the locus used to describe

A

a sequence of DNA situated on a specific region on a chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

DNA is…

A

a double-stranded structure consisting of 2 nucleotides held together by hydrogen bonds between the bases in opposing (anti-parallel) strands

17
Q

DNA molecules are organised into stretches of sequence called…

A

genes

18
Q

Richard Dawkins described genes as

A

any portion of chromosomal material that potentially lasts for enough generations to serve as a unit of natural selection

19
Q
  1. each gene has one or more …
  2. each gene can … with another gene
  3. each gene can … into different forms
  4. genes are expressed at …
  5. a gene can only influence human development when…
  6. for DNA to impart information it must be …
A
  1. specific effects upon the phenotype of the organism
  2. recombine
  3. mutate
  4. different time points in life
  5. its turned on and expressed
  6. transcribed
20
Q

The strand of DNA acts as a … for the synthesis of ….

A
  1. template

2. ribonucleic acid (RNA)

21
Q

RNA forms stable structures by …

A

base-pairing (like DNA)

22
Q

DNA information can be … to RNA for …

A
  1. copied

2. transcription and translation and carried to other areas of the cell to create proteins

23
Q

what do messenger RNA do?

A

carry instructions specifying sequences of amino acids

24
Q
  1. groups of … of mRNA …
    - > these groups are called …
    - > how many potential codons & amino acids?
A
  1. 3 bases
  2. serially code for each amino acid
    - > codons
    - > 64 codons, 20 different amino acids
25
Q

Protein types

A
  • enzymes
  • haemoglobin
  • insulin
  • collagen
  • keratin
  • histones
  • actin and myosin
  • immunoglobulins
26
Q

what are alleles?

A
  • 1/3 of human genes have two or more different forms called alleles
  • one or two or more forms (or variations) of a gene
27
Q

the alleles of a give gene ….

A

influence the same trait or characteristic e.g. eye colour

-> different allele forms result in different eye colours

28
Q

Geneticists track the sequence of one strand of DNA complex because…

A

the other is determined by the complementarity rule

29
Q
  1. homozygous alleles example

2. heterozygous example

A
  1. F: AAG T TGG
    M: ATC T ACG
  2. F: AAG A TGG
    M: ATC T AGC

(look at middle letter)

30
Q
  1. dominant allele is …

2. recessive allele is expressed when…

A
  1. expressed if present

2. expressed if dominant is absent

31
Q

What is polygenic inheritance?

A
  • when traits are governed by more than one gene
32
Q

What is mitosis?

A
  • process of cell replication and division in which the cell separates the chromosomes in the cell nucleus into 2 identical sets, 2 separate nuclei
    = genetically identical
33
Q
  • What is meiosis necessary for?
  • what does it produce?
  • what happens?
A
  • sexual reproduction
  • gametes
  • DNA replicated, recombined and the cell divides twice
34
Q
  1. Mitosis = each daughter cell with … chromosomes

2. meiosis = each daughter cell with … chromosomes

A
  1. 46

2. 23

35
Q
  1. Mitosis = how many daughter cells

2. meiosis = how many daughter cells

A
  1. 2

2. initially 2 -> split into 4

36
Q

mutation definition

-> source of ?

A

the process of change in the sequence of DNA

-> genetic variation and basis for natural selection

37
Q

How do mutations occur?

A
  • spontaneously

- or induced by external factors e.g. exposure to chemicals

38
Q

4 main types of mutations

A
  • base substitutions
  • deletions of DNA
  • insertions of DNA
  • whole or partial chromosomal abnormalities
39
Q

How does Turner’s syndrome affect development?

  1. intellectual
  2. physical
  3. sexual
A
  1. intellectual disability
  2. movement control problems
  3. 99% present as female