Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

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
X-Linked inheritance
Genes carried on X chromosome Usually only affects males
26
Lyonization definition
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)
27
3 Non-Mendelian Inheritance Pathways
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
28
How do you identify a condition has a genetic component?
- Family studies - Twin studies - Adoption studies
29
What do we compare in family studies?
If Multifactorial: Risk of condition in relatives of affected individual is higher than in general population.
30
What do you compare in twin studies?
If genetic component: Concordance rate is higher in monozygotic twins than dizygotic twins. If Multifactorial: High risk for MZ twins even when reared apart
31
What do we compare in adoption studies?
If Multifactorial: Adopted children of affected parents have high risk of developing disease.
32
Characteristics of Multifactorial inheritance
- Incidence is greatest among relatives (Familial incidence > Population incidence)
33
GWAS - Genome Wide Association Studies
Most genetic variations still result in a functioning gene - polymorphism. Compare the frequency of SNP (single nucleotide polymorphisms) in patients and healthy controls.
34
List environment agents acting on embryogenesis
- Drugs and chemicals e.g. thalidomide, alcohol - Maternal Infections e.g. rubella - Physical agents e.g. radiation - Maternal illness e.g. diabetes
35
Where is the DNA inside the cell?
95% nucleus 5% mitochondria
36
Describe structure of DNA
- Double helix coiled around nucleosomes and then supercoils again into chromosomes. A=T C=G
37
What is mitosis for?
Produces two genetically identical daughter cells for growth and to repair dead cells.
38
Describe steps of mitosis
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
Clinical relevance (drugs to treat cancer)
Mitotic spindle - Taxol Spindle poles - Ispinesib Anaphase - Colchicine
40
Describe meiosis
Two cell divisions to form 4 haploid daughter cells (gametes)
41
When does random crossing over occur?
Prophase 1
42
Describe sperm production
At puberty, meitotic divisions produce equal gametes and takes 60-65 days.
43
Describe egg production
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
Non-disjunction
When chromosome pairs or chromatids fail to separate
45
Down syndrome %
75% Maternal meiosis 1 25% maternal meiosis 2 3-5% paternal non disjunction
46
What is gonadal mosaicism?
Genetic mutation only in ova or spermatozoa so parent is healthy but get us may not be.
47
Eugenics
Positive eugenics - Blood relatives reproduced to preserve good/noble genetics Negative eugenics - Sterilisation in Germany to remove ‘bad’ genetics
48
What is genetic counselling?
When patients/relatives at risk of hereditary disease are advised of consequences and prevention = Should be Non directive and non judgemental
49
Screening vs diagnostic test
Screening identifies increased risk Diagnostic confirms condition
50
Adv and Dis of Non Invasive Prenatal Testing
Adv - Fewer miscarriages, later TOP= less trauma Dis - More pressure to have NIPT = lack of information, failed results, increases social pressure to TOP
51
Pre-Implantation Genetic Diagnosis
If risk of conceiving with serious condition is >10% IVF offered and only embryos without gene placed into womb.
52
Adv and Dis for Mitochondrial Replacement Therapy
Adv - Nuclear DNA intact so minimal risks Dis - Any modification is inheritable, ethics
53
Name some types of DNA variants
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
What is non pathogenic DNA polymorphism?
Amino acid change conserved through evolution (not disease causing)
55
Locus heterogeneity
Variants in different genes give same clinical condition e.g. hypertrophic cardiomyopathy
56
3 mechanisms of dominance
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
Diagnostic vs predictive vs screening
Diagnostic- if symptoms, genetic test confirms clinical diagnosis Predictive - Testing health-at-risk family members Screening - Targets populations
58
Sanger vs next generation screening
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
What are incidental/ secondary findings?
Additional findings discovered during an investigation but don’t explain symptoms. (Need to consider if to disclose = ethical issues with consent)
60
What is a female germ cell?
Oocyte / ovum / egg
61
What is a male germ cell?
Sperm
62
What is the names of zygote to foetus
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
Embryology: week 1 summary
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
Embryoblasts vs Trophoblasts
B - forms embryo T - Forms placenta
65
Embryology: week 2 summary
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
Embryology: week 3 summary
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
What does ectoderm differentiate into?
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
What does endoderm differentiate into?
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
What does the mesoderm differentiate into?
Musculoskeletal system Deep layers of skin Walls (not lining) of bowel Urogenital system Abdominal and chest walls + lining
70
Describe formation of the notochord (week 3)
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
Embryology: week 4 neurulation summary
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
What happens if week 4 fusion does not extend all the way
To caudal = Spina bifida To cranial = anencephaly
73
Embryology: week 4 mesoderm
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
Embryology: Describe week 4 folding
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
Homoplasmy vs Heteroplasmy
Homo - eukaryotic cell with identical mitochondrial DNA Hetero - multiple copies of mtDNA due to mutations
76
Define Multifactorial conditions
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.
© 2025 Bold Learning Solutions. Terms and Conditions