Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Phase 1 Notes > IMMS - Genetics + Embryology > Flashcards

IMMS - Genetics + Embryology Flashcards

1
Q

Difference between Euchromatin and Heterochromatin

A

Euchromatin - less condensed, lighter, transcripted

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

Describe phases in mitosis

A

(24hrs)
Interphase
Prophase
Metaphase
Anaphase
Telophase

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

What are the arms of a chromatid?

A

p (petite)
q

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

What is karyotyping?

A

Allowing chromosomes to produce visible patterns we can study.

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

Different chromosome abnormalities

A

Numerical:
- Trisomy
- Monosomy
- Polyploidy
Structural
- Translocation
- Inversion
- Duplication
- Deletion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Example of non-disjunction

A

Down syndrome(21), Edwards syndrome(18), Patau syndrome(13)

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

Describe 3 different translocations

A

Reciprocal translocation - bit of chromosome broken off and stuck to another (balanced)
Robertsonian translocation - chromosome joins to another
Unbalanced rearrangement:
‘Cri Du Chat’ deletion of 5p
Prader Willi/Angelman deletion of 15q

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

FISH Summary

A

To study chromosome abnormalities :
-Add flourophores to DNA probes
- Hybridise probes to chromosome

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

Describe microarrays

A

Many holes on a slide containing different probes to assess all sections of a chromosome at a time.

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

Constitutional vs Acquired

A

Constitutional- Occurs at gametogenesis, affects all cells and is heritable.
Acquired - Occurs during lifetime, restricted to malignant tissue and often not heritable.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are cytogenetics for?

A

Look for abnormalities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Genotype vs phenotype

A

Phenotype is appearance of an individual due to the environment and genetic constitution (genotype)

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

Homozygous vs Heterozygous vs Hemizygous

A

Heterozygous - Different Alleles at locus
Hemizygous - Only one allele (refers to X chromosome in male)

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

What causes genetic diversity in gametes?

A

Independent segregation

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

In a pedigree drawing, what do these symbols mean: circle, square, triangle, shaded, line through, diamond

A

Circle - Girl
Square - Boy
Shaded - affected
Triangle - miscarriage
Diamond - don’t know gender
Line through - deceased

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

Autosome vs Heterosome

A

Autosome is any other chromosome than sex chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Alleles heterogeneity

A

Different mutations in the same gene results in the same condition eg cystic fibrosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Autosomal recessive inheritance

A

Needs two recessive alleles to be expressed.
Carrier parents have 1/4 offspring risk.
Healthy sibling have 2/3 chance of being a carrier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Calculating risk of autosomal recessive

A

Chance mother is a carrier x chance father is a carrier x risk if both carriers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is consanguinity?

A

Reproduction between two relatives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Autosomal dominant Inneritance

A

Once need one allele to be expressed.
Affects individuals in multiple generations
Male and females equally affected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Penetrance vs Expressivity

A

% with genotype showing expected phenotype
Vs
Range of phenotypes expressed with genotype (severity, age of onset)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Definition of anticipation

A

Genetic disorders affect successive generations earlier or more severely due to unstable triplet repeat sequences.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Somatic vs Gonadal(germ line) Mosaicism

A

Somatic- Genetic fault only present in some tissue (De Novo and not inherited)
Gonadal - Genetic fault only in reproductive tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

X-Linked inheritance

A

Genes carried on X chromosome
Usually only affects males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Lyonization definition

A

Only one of 2 X chromosomes are active in each female cell. Normally 1/2 cancel but can sometimes be skewed and switches on variant chromosome (symptoms as a carrier)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

3 Non-Mendelian Inheritance Pathways

A

Imprinting - Epigenetic influence causes specific parents genes to be expressed (e.g. deletion of paternal gene)
Mitochondrial DNA - Inherited from mother, mutation may affect different tissues
Multifactorial Inheritance - combination of genetic and environmental factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How do you identify a condition has a genetic component?

A
  • Family studies
  • Twin studies
  • Adoption studies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What do we compare in family studies?

A

If Multifactorial:
Risk of condition in relatives of affected individual is higher than in general population.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What do you compare in twin studies?

A

If genetic component:
Concordance rate is higher in monozygotic twins than dizygotic twins.
If Multifactorial:
High risk for MZ twins even when reared apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What do we compare in adoption studies?

A

If Multifactorial:
Adopted children of affected parents have high risk of developing disease.

32
Q

Characteristics of Multifactorial inheritance

A
  • Incidence is greatest among relatives
    (Familial incidence > Population incidence)
33
Q

GWAS - Genome Wide Association Studies

A

Most genetic variations still result in a functioning gene - polymorphism. Compare the frequency of SNP (single nucleotide polymorphisms) in patients and healthy controls.

34
Q

List environment agents acting on embryogenesis

A
  • Drugs and chemicals e.g. thalidomide, alcohol
  • Maternal Infections e.g. rubella
  • Physical agents e.g. radiation
  • Maternal illness e.g. diabetes
35
Q

Where is the DNA inside the cell?

A

95% nucleus
5% mitochondria

36
Q

Describe structure of DNA

A
  • Double helix coiled around nucleosomes and then supercoils again into chromosomes.
    A=T
    C=G
37
Q

What is mitosis for?

A

Produces two genetically identical daughter cells for growth and to repair dead cells.

38
Q

Describe steps of mitosis

A

Interphase - DNA and organelle replication
Prophase - DNA condenses and microtubules form
Metaphase - nuclear membrane breaks down and homologous chromosomes line equator
Anaphase - sister chromatids pulled to poles
Telophase - Nuclear membrane reforms and DNA unfolds
Cytokinesis - Splitting of cell

39
Q

Clinical relevance (drugs to treat cancer)

A

Mitotic spindle - Taxol
Spindle poles - Ispinesib
Anaphase - Colchicine

40
Q

Describe meiosis

A

Two cell divisions to form 4 haploid daughter cells (gametes)

41
Q

When does random crossing over occur?

A

Prophase 1

42
Q

Describe sperm production

A

At puberty, meitotic divisions produce equal gametes and takes 60-65 days.

43
Q

Describe egg production

A

Primordial germ cell mitosis 30x to oogonia.
Cells enter ovulation 10-50 years later and cytoplasm divides unequally - 1 egg and 3 tiny polar bodies. meiosis 1 is completed at ovulation, Meiosis 2 only if fertilisation occurs.

44
Q

Non-disjunction

A

When chromosome pairs or chromatids fail to separate

45
Q

Down syndrome %

A

75% Maternal meiosis 1
25% maternal meiosis 2
3-5% paternal non disjunction

46
Q

What is gonadal mosaicism?

A

Genetic mutation only in ova or spermatozoa so parent is healthy but get us may not be.

47
Q

Eugenics

A

Positive eugenics - Blood relatives reproduced to preserve good/noble genetics
Negative eugenics - Sterilisation in Germany to remove ‘bad’ genetics

48
Q

What is genetic counselling?

A

When patients/relatives at risk of hereditary disease are advised of consequences and prevention
= Should be Non directive and non judgemental

49
Q

Screening vs diagnostic test

A

Screening identifies increased risk
Diagnostic confirms condition

50
Q

Adv and Dis of Non Invasive Prenatal Testing

A

Adv - Fewer miscarriages, later TOP= less trauma
Dis - More pressure to have NIPT = lack of information, failed results, increases social pressure to TOP

51
Q

Pre-Implantation Genetic Diagnosis

A

If risk of conceiving with serious condition is >10% IVF offered and only embryos without gene placed into womb.

52
Q

Adv and Dis for Mitochondrial Replacement Therapy

A

Adv - Nuclear DNA intact so minimal risks
Dis - Any modification is inheritable, ethics

53
Q

Name some types of DNA variants

A

Deletion (can cause frame shift)
Splice-site = Intron translated
Duplication, Random mutations
Non-sense = Changes to stop codon
Mis-ense = single base substitution changes amino acid
Expansion of tri-nucleotide repeats = gets bigger in next generation so more severe symptoms

54
Q

What is non pathogenic DNA polymorphism?

A

Amino acid change conserved through evolution (not disease causing)

55
Q

Locus heterogeneity

A

Variants in different genes give same clinical condition e.g. hypertrophic cardiomyopathy

56
Q

3 mechanisms of dominance

A

Loss of function variant - only one allele functioning
Gain of function variant - increased protein activity
Dominant- negative variant - protein from variant allele interferes with normal protein

57
Q

Diagnostic vs predictive vs screening

A

Diagnostic- if symptoms, genetic test confirms clinical diagnosis
Predictive - Testing health-at-risk family members
Screening - Targets populations

58
Q

Sanger vs next generation screening

A

Sanger - Uses PCR to amplify regions of interest. Slow, high cost per gene but very accurate

Next - Whole genome sequenced.
Fast, low cost per gene but moderately accurate

59
Q

What are incidental/ secondary findings?

A

Additional findings discovered during an investigation but don’t explain symptoms.
(Need to consider if to disclose = ethical issues with consent)

60
Q

What is a female germ cell?

A

Oocyte / ovum / egg

61
Q

What is a male germ cell?

A

Sperm

62
Q

What is the names of zygote to foetus

A

Zygote - At fertilisation
Blastomeres - early embryonic cells
Morula - 12-32 blastomeres
Blastocyst - Morula enters uterine cavity
Gastrula - Embryonic disc forms
Neurula - Neural tube forms
Embryo - Developing till end of week 8
Foetus - week 9 to birth

63
Q

Embryology: week 1 summary

A

Day 1 (stage 1) - Fertilisation
Day 2 (stage 2)- Fusion of two haploids form zygote
Day 3 - formation of morula (12-32 blastomeres)
Day 4 (stage 3) - Zona Pellucida degenerates
Day 5 - shedding of ZP hatches late blastocyst
Day 6 (stage 4) - Syncytio and cytotrophoblasts attach blastocyst to endometrial epithelium

64
Q

Embryoblasts vs Trophoblasts

A

B - forms embryo
T - Forms placenta

65
Q

Embryology: week 2 summary

A

Day 8 - Inner blastomeres separate by basement membrane to form bilaminar disc
Day 9 - Formation of yolk sac and amniotic cavity
Day 10 - lacunae appear and primary yolk sac forms
Day 12 - Cavities become confluence to form extra embryonic coelom
Day 13 - Chorionic vesicles joins to placenta cells to form umbilical cord

66
Q

Embryology: week 3 summary

A

As ectoderm grows, folding along the caudal midline creates primitive streak. Cells from the base of primitive streak migrate between ectoderm and endoderm to form mesoderm. (Gastrulation)
= Trilaminar disc

67
Q

What does ectoderm differentiate into?

A

Epidermis of skin, hair, nails
Mammary, sweat, sebaceous glands
Central + Peripheral NS
Pituitary gland
Teeth enamel
Sensory epithelium of nose, ear and eye
Eye lens and inner ear

68
Q

What does endoderm differentiate into?

A

Development of notochord
Epithelial lining of tympanic cavity + auditory tube
Epithelial lining of GI, respiratory and urinary bladder
Parenchyma of thyroid, parathyroid gland, liver + pancreas

69
Q

What does the mesoderm differentiate into?

A

Musculoskeletal system
Deep layers of skin
Walls (not lining) of bowel
Urogenital system
Abdominal and chest walls + lining

70
Q

Describe formation of the notochord (week 3)

A

From end of primitive streak to cranial end, tube fuses with endoderm to become a groove.
Plate infolding to form notochord - role in further midline development as provides mechanical + signalling cues

71
Q

Embryology: week 4 neurulation summary

A

Differentiation of ectoderm to form neural plate bending to form neural crest. Closure disconnects cells to form peripheral nervous system. Notochord degenerates only persisting as nucleus pulposus.

72
Q

What happens if week 4 fusion does not extend all the way

A

To caudal = Spina bifida
To cranial = anencephaly

73
Q

Embryology: week 4 mesoderm

A

Mesoderm differentiates between cranial and caudal to form:
Paraxial mesoderm differentiates into paired cuboidal somites (Develop craniocaudally) which form sclerotium’s, myotome and dermatome.
Intermediate mesoderm form urogenital system
Lateral mesoderm split and form parietal + visceral layers

74
Q

Embryology: Describe week 4 folding

A

Lateral folding - mesoderm fold to form intraembryonic coelom and ectoderm grow to form superficial skin. Endoderm fuse at midline to form primitive gut tube.
Cephalic to caudal folding - cranial flexion brings heart to thoracic and septum transversum to diaphragm. Caudial folding moves primitive streak caudally and Allantois is incorporated into embryo.

75
Q

Homoplasmy vs Heteroplasmy

A

Homo - eukaryotic cell with identical mitochondrial DNA
Hetero - multiple copies of mtDNA due to mutations

76
Q

Define Multifactorial conditions

A

Disease due to a combination of genetic and environmental factors

Phase 1 Notes (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions