Lesson #2 Flashcards
23rd pair of chromosomes:
Sex chromosomes.
1st-22nd chromosomes:
Autosomes.
Meiosis:
Sexual reproduction, produces 4 haploid gametes (Sperm or eggs) - These are genetically unique due to crossing over and independent assortment.
Mitosis:
Produces genetically identical, diploid, cells.
Genotype:
Genetic coding for a specific trait.
Gene nomenclature in mice and rats:
Gene symbol - Sox2 (in italics)
Protein designation - SOX2
Gene nomenclature in humans, primates, and domestic species:
Gene symbol - SOX2 (in italics)
Protein designation - SOX2 (not in italics)
The short arm of chromosome:
P arm.
The long arm of chromosome:
Q arm.
Polygenic traits:
multiple genes located on more than one chromosome contributing to 1 trait - eye color/skin tone.
The additive effects of many abnormal genes and environmental factors, that will be passed down in families?
Multifactorial events.
Examples of multifactorial events:
Obesity, hypertension, atherosclerosis, and diabetes.
What can occur from a single gene or a chromosomal defect?
Genetic disorders.
This may occur spontaneously or due to toxic substances - such as radiation, chemicals, etc.
Genetic mutations.
True or false - Single gene mutations in both autosomes and sex chromosomes are spread to offspring?
FALSE - single gene mutations are passed down in sex chromosomes, but not in autosomes.
Mendelian traits are caused by:
Inheritance of defective alleles - either 1 (dominant) or 2 (recessive) alleles.
True or false - X-linked dominant and recessive genes are examples of non-mendelian inheritance.
True!
_______ ________ ________ normally affect structural proteins and receptors.
Autosomal dominant mutations.
_________ ________ _________ normally cause defective enzymes.
Autosomal recessive mutations.
True or false - Sex-linked recessive genes are most commonly expressed in men because they only have one X and do not need two alleles.
True!
The process that inactivates one X chromosome in women, for gene dosage compensation, is called:
X-Inactivation.
When does X-Inactivation occur? What pattern does it follow?
X-Inactivation occurs in the early blastocyst stage, and will replicate that X gene via mitosis to create a mosaic pattern.
What amount of genes will escape X-Inactivation?
1/4 of genes on an inactive X will escape.
What syndrome is due to an overdose of escaped genes in X-inactivation? What sex chromosomes would it have?
- Klinefelter syndrome.
- XXY
What syndrome is due to a lack of escaped genes in X-Inactivation? What sex chromosomes would it have?
- Turner syndrome.
- X.
___-______________ is due to an unequal separation of chromosomes in meiosis 1, giving either 22 or 24 chromosomes in gametes.
Non-disjunction, a chromosomal abnormality.
Non-disjunction will occur when?
During mitotic divisions in early embryonic phase - causing mosaicism.
What is the name for an interchange of chromosome parts between 2 or more non-homologous chromosomes?
Translocation, a chromosomal abnormality.
The 2 types of translocation - Describe them:
- Reciprocal - Some chromosomes will receive extra copies, while others will receive fewer copies than normal. No chromosome parts are lost.
- Non-reciprocal - also called robertsonian translocations. When the long arms of a chromosome become bound to a common centromere, and the short arms of the chromosome are lost.
Chromosomes for klinefelters syndrome?
XXY
Chromosomes for turner’s syndrome?
X
Lethal chromosomes?
Y
Down syndrome chromosomes:
47 chromosomes, trisomy 21.
Patau syndrome chromosomes:
47 chromosomes, trisomy 13.
Edwards syndrome chromosomes:
47 chromosomes, trisomy 18.
Which two trisomies are due to robertsonian translocations?
Trisomy 21 and trisomy 13 (downs and patau)
True or false? 60-70% of spontaneous abortions in the first trimester are due to some form of trisomy?
FALSE - Only 40-50% of spontaneous abortion in the first trimester is due to trisomy.
What products do we get from non-disjunction in meiosis 1?
2 diploid gametes and 2 gametes with no chromosomes - All 4 SHOULD be haploid.
What products do we get from non-disjunction in meiosis 2?
2 normal haploid gametes, 1 diploid gamete, and one gamete with no chromosomes - All 4 SHOULD be haploid.
__________ __________ is caused by a balanced chromosomal translocation of the telomeric portion of chromosome 22Q and chromosome 9Q, and vice versa.
Philidelphia chromosome.
True or false - The translocated fragment on a Philadelphia chromosome is non-functional.
FALSE - The translocated fragment of a Philidelphia chromosome IS functional.
What type of translocation disorder occurs when the mother of the affected child has 45 chromosomes, where the long arms of chromosomes 21 and 14 translocate?
Translocation down syndrome - an example of a robertsonian translocation.
What does the philidelphia chromosome produce?
Philidelphia chromosome produces a strong tyrosine kinase that causes malignant transformation. BAD!
Mitochondria:
- Arise by division of pre-exisiting mitochondria.
- Has it’s own it’s own genetic machinary.
- Has some functional mDNA proteins, but mostly utilizes nDNA.
True or false: Homoplasmy is where mitochondria are inherited in a mixture of normal and mutant.
FALSE - Homoplamsy is when mitochondria are inherited either entirely mutant or entirely normal.
____________ is when daughter cells receive a mixture of mutant and normal mitochondria.
Heteroplasmy.
_______ pass down mitochondrial DNA, but ________ offspring are affected
Female, all.
If a cardiac glycoside does not become resolved, it can cause damage to the mitochondria - this is called:
Calcium overload:
