Genetics Flashcards
(72 cards)
1
Q
Mendal’s Laws
A
- Law of dominance and uniformity
- Some alleles are dominant, and others recessive
- If two homozygotes with different alleles breed, then the offspring will all be heterozygotes with the phenotype of the dominant allele. - Law of segregation
- During gamete formation, the alleles of each genes separate into separate gametes - Law of independent assortment
- Alleles are passed on separately of each other
2
Q
P
A
Parental generation
3
Q
F1
A
First filial generation
4
Q
F2
A
Second filial generation
5
Q
Incomplete dominance
A
The heterozygous offspring shows a phenotype distinct from the two possible homozygous phenotypes
6
Q
Codominance
A
Where both alleles of a heterozygote are expressed and thus traits are neither dominant nor recessive
7
Q
Telomere sequence
A
TTA GGG
Tell them all, Genes gotta go
8
Q
Telomere function
A
- Protect exonucleases from degrading genes
- Prevent chromosome fusion
- Enhance chromosome stability
- Protect the end of chromosome from being recognized as DNA breaks, which would otherwise trigger mechanisms or degradation.
- Solution to the end of replication problem: DNA polymerase enzyme needs a 3’ end to add nucleotides; this is not available at the end of the chromosome of the lagging strand
9
Q
Chromosomes get _____ in size as the number increases.
A
Smaller
10
Q
How to obtain the karyotype?
A
- Take the sample (Blood, amniotic fluid, and tissue)
- Metaphase arrest (Halt the cell cycle at metaphase)
- Chromosome staining and analysis
- Karyotype interpretation
11
Q
Denote a healthy female’s karyotype
A
46, XX: 22 pairs of autosomes and 2X chromosomes
12
Q
Denote a healthy male’s karyotype
A
46, XY: 22 pair of autosomes and 1X and 1Y chromosome
13
Q
Denote a female with Down syndrome
A
47, XX +21
14
Q
Denote a male with Down syndrome
A
47, XY +21
15
Q
Denote a female with monosomy on chromosome number 5
A
45, XX -5
16
Q
How are chromosomes ordered in a karyotype?
A
- Size
- Location of centromere
- Homologous pairs
17
Q
How do we denote a human karyotype?
A
Number of chromosomes, (comma) sex chromosomes, and plus or minus sign to signify any anomaly
18
Q
Ploidy
A
Number of set(s) of chromosomes
For example,
Haploid (1n) 23 chromosomes
Diploid (2 set of 23 chromosomes = 46 chromosomes)
Polyploid (3n, 4n)
Aneuploidy (2n + 1, 2n -1, etc)
Anucleate (No chromosome)
19
Q
Polyploidy
A
Containing more than two sets of chromosomes
- triploidy
- tetraploidy
20
Q
Aneuploidy
A
Abnormal number of chromosomes
- trisomy (2n+1)
- monosomy (2n-1)
- tetrasomy (2n+2)
- nullisomy (2n-2)
21
Q
Types of mutation
A
- Gene mutations
- Chromosomal mutation
- Genomic mutation
22
Q
Gene mutation types.
A
- Point mutation
- substitution
- inversion - Frameshift mutation
- insertion
- deletion
23
Q
Chromosomal mutation
A
- Deletion
- Duplication
- Inversion
- Translocation
- Insertion
24
Q
Genomic mutation
A
- Polyploidy
- Aneuploidy
25
Where can mutation occur?
- nucleus, mitochondria, chloroplast, nucleoid, plasmids, and viral genome
(Basically wherever there is a genetic material)
26
Causes of mutations
- Spontaneous
1. DNA replication errors
2. DNA repair errors
3. Mitosis/ meiosis errors
4. Spontaneous chemical changes
- Induced causes
1. chemicals
2. radiation
3. Pathogens
27
Types of genetic mutations according to the effect
1. Silent mutation
2. Missense mutation
3. Nonsense mutation
4. Stop codon suppression
28
What is chromosomal inversion mutation and how can it affect the phenotype?
Macro region of chromosome breaks and reattaches to the same chromosome in a reverse orientation.
- disrupt gene regulation and Gene order
- can affect chromosome pairing during meiosis
29
Chromosomal translocation mutation types, descriptions of each type, and how it affects the phenotype
1. Reciprocal translocation
- exchange of macro segments between two non-homologous chromosomes
2. Robertsonian translocation
Entire chromosome has attached to another chromosome
30
Insertion
Portion of one chromosome has been taken from its normal place and inserted into another chromosome
31
What is Mosaicism ?
When certain cells have a mutation in their genes but others do not, a single organism has two or more genetically distinct cell lines. This means that sample from one tissue might not detect the mutation.
32
True or false: if a human cell does not divide by mitosis, it must not be a somatic cell.
False: the statement is not always true because there are some cells such as neurons, erythrocytes, skeletal muscle cells, and cardiac muscle cells that do not undergo mitosis or cell division.
33
A group of genes in prokaryotic cells that performs gene regulation, and contains mutiple structural genes that code for mutiple polypeptide chains.
Operon
34
35
Compartments of operon
1. Promoter
2. Repressor
- inducer
- co-repressor
3. Operator
4. Structural genes
36
Lac Operon
1. There are three structural genes that produce proteins to digest lactose.
2. The repressor is typically bound to the operator when there is no lactose in the environment.
3. When there is lactose in the environment, the allolactose acts as an inducer binds to the repressor, dissociating it from the operator region.
4. When it happens, the polymerase binds to the promoter and starts transcribing the structural genes.
37
Three structural genes of lac Operon and proteins that they produce.
LacZ: Beta-galactosidase (breaks down lactose into glucose and galactose)
LacY: Lactose permease (transport lactose into cell)
LacA: Transacetylase (metabolism of other sugars)
38
The operator is said to be turned (blank) when the repressor is bound.
Off
39
(Blank) produces repressor that binds to the operator region.
Regulatory gene from upstream of the operon
40
_____ is the inducer for lac Operon.
Allolactose
41
Allolactose acts as _____ in lac Operon.
Inducer
42
Tryptophan acts as _____ in Trp operon
Co-repressor
43
Trp-operon process
1. Normally, when there is no tryptophan in the environment, the repressor is not bound to the operator, and the structural genes are being transcribed.
2. When there is tryptophan in the environment, it acts as a co-repressor, and the repressor binds to the operator, stopping the transcription process.
3. The structural genes consist of five different genes.
44
Tryptophan structural genes
TrpE
TrpD
TrpC
TrpB
TrpA
45
What is the name for gene regulation to switch genes on and off?
Epigenetic modification
46
Types of epigenetic modification
1. Histone modification
- acetylation (generally loosen up the chromatin and increases gene expression)
- methylation (either activate or repress gene expression, which depends on the specific methylation site or the number of methyl group added)
- phosphorylation, ubiquitylation
2. DNA modification
- methylation (generally reduces gene expression, and silences transcription)
3. Non-coding RNAs (ncRNAs)
- translational repression
- mRNA degradation, and suppression
- Promote genomic integrity and stability
- Recruiting chromatin-remodeling complexes to specific genes
- Interacts with chromatin-modifying enzymes and guides them to specific DNA regions, influencing, whether a region of DNA is condensed or relaxed and affecting gene transcription.
47
Non-coding RNAs
1. Regulatory ncRNA
Micro RNA
Long non-coding RNA
Piwi interacting RNA
Small interfering RNA
Small nuclear RNA
Small nucleolar RNA
2. Housekeeping ncRNA
tRNA
rRNA
48
Eukaryotic gene structure
1. Enhancer/ Silencer
2. Promoter
- proximal
- core
3. 5’ untranslated region
4. Open reading frame
- introns
- extrons
5. 3’ untranslated region
-terminator
6. Enhancer/ Silencer
49
In eukaryotes, (blank) binds to the (blank) region for gene regulation
1. Activators, enhancer region
2. Repressor, silencer region
50
Where can enhancers and silencers locate at in eukaryotes?
Upstream, downstream or even within the gene
51
Transcription factors that bind to the enhancer in eukaryotes
Activators
52
Transcription factors that bind to the silencer in eukaryotes
Repressor
53
Types of transcription factors in eukaryotes
1. General transcription factors
2. Activators
3. Repressor
54
What do general transcription factors do in eukaryotes?
General transcription factors together with DNA polymerase enzymes bind to the promoter region and initiate transcription.
55
56
Where is the promoter at, what are the different regions of the promoter, and what are their functions?
Promoter region is at the immediate upstream of the coding region.
There are two different regions of the promoter which are the core promoter and the proximal promoter.
The core promoter region is where the DNA polymerase and general transcription factors bind to. The proximal promoter region assist regulate how often transcription starts by interacting with additional transcription factors.
57
Does five prime untranslated region gets transcribed into mRNA?
Yes
58
Starting from which part, does the DNA get transcribed?
At the end of the promoter region, and at the start of five prime untranslated region.
59
What is the component of a eukaryotic gene that actually encodes a protein called?
Open Reading frame (from start codon to stop codon)
60
Does the entirety of the open reading frame get translated into protein?
No, the open reading frame contains introns, which are spliced out during the post transcriptional process.
61
Where is the terminator in eukaryotic gene sequence?
Downstream of the three prime untranslated region.
62
The compartments of the heterogeneous RNA
Five prime untranslated region
Open Reading frame
Three prime untranslated region
63
Cells death types
. Apoptosis
. Necrosis
64
What is autophagy?
It is when cell organelles are degraded to be recycled or for energy. It can occur to damaged organelles, proteins, or low energy.
First, the organelle is induced it into a vesicle, which we call it autophagosome . The autophagosome is fused with a lysosome. The autolysosome breaks down the organelle.
65
What is apoptosis?
Apoptosis is programmed cell death, which is a highly regulated and controlled process.
1. Cell shrink due to the breakdown of the cytoskeleton and the loss of cell membrane rigidity.
2. Chromatin condensation.
3. Membrane blebbing. Cell membrane forms bubble-like blebs.
4. Formation of apoptotic bodies: the cell breaks apart into smaller membrane-bound vesicle
5. Phagocytosis occurs.
66
What is Grifiths experiment and what did it prove?
Grifiths experiment proved the transformation (horizontal gene transfer between bacteria) by using two strains of streptococcus pneumoniae -one avirulent rough strain and one virulent smooth strain- on mice.
67
Describe the Griffiths experiment.
The Griffiths experiment uses two different strain of streptococcus pneumonia: the small strain and the rough strain.
The smooth strain contains a capsule that surrounds the bacterium, which protects it from the immune system of the mouse.
When the smooth strain is injected, the mouse dies.
When the rough strain is injected, the mouse survives.
When the heated smooth strain is injected, the mouse survives.
When the heated smooth strain is mixed with the rough strain, and it is injected into the mouse, the mouse dies, proving that genetic materials are transferred between bacteria horizontally.
This experiment proves the transformation . Transformation is a type of horizontal, genetic transfer where a bacterium picks up, genetic material from a surrounding, typically from a lysed bacteria.
68
When is Griffith’s experiment conducted?
1928
69
Why does the virulent strain of streptococcus pneumonia is called the smooth strain?
It is because the strain has a smooth appearance on agar plates due to its capsule made out of polysaccharides, which protects the bacteria from the host immune system, making it virulent.
70
What are the types of horizontal gene transfer?
Transformation is when a bacteria picks up genetic materials from the surrounding, typically from a lysed bacteria
Transduction is when a bacteriophage accidentally injects fragments of bacterial DNA while infecting bacteria.
Conjugation is transfer of genetic material between two bacteria through direct contact, pili, and mating bridge.
71
What is vertical gene transfer?
Vertical gene transfer is transfer of genetic material through reproduction from parent to offspring.
72
What is the physiological state that allows transformation (a type of horizontal transfer)?
Competence
