Term
| What is the difference between chromosome and chromotid? |
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Definition
chromosome is the architecture of DNA
chromatid is chromosomes plus the relevant proteins (histons) |
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Term
| What does transcription code and where is it coded? |
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Definition
| mRna, in the cell nucleus |
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Term
| What is the p arm of a chromosome? |
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Definition
| the p arm is the short arm of the chromosome. |
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Term
| What is the q arm of the chromosome? |
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Definition
| The q arm is the long arm of the chromosome |
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Term
| What is genetic imprinting? |
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Definition
| this is the silence of a gene when heterozygote homologous pairs exist |
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Term
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Definition
| variations of genes. If a gene is a code for a trait, alleles help you differentiate the variations (allele) of that trait (gene) |
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Term
| Generally speaking, what are genes? |
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Definition
| genetic material on a chromosome that codes for a trait |
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Term
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Definition
| The set of alleles an organism carries |
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Term
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Definition
| the physical expression of the genotype |
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Term
| Generally speaking, what are the two broad categories of cells? |
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Definition
Germ cells: form gametes
Somatic cells: all other cells of the body |
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Term
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Definition
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Term
| Genetically normal humans contain how many pairs of homologous chromosomes? |
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Definition
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Term
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Definition
Ploidy: The number of copies of individual homologous chromosomes.
Haploid: 1 copy
Diploid: 2 copies
etc
etc |
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Term
| In terms of genetics, what is the n used to denote? |
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Definition
| n is the copies of chromosomes of the homologous set |
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Term
| Divion that starts with a diploid 2n cell and ends with 2 diploid 2n cells is called? |
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Definition
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Term
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Definition
| Nuclear division, the separation of the chromatids |
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Term
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Definition
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Term
| Division that starts with a diploid 2n cell and ends up with 4 haploid 1n cells is called? |
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Definition
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Term
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Definition
non-disjunction is the failure of chromosomes to separate during mitosis or meiosis.
this is a major reason for chromosome abberations and spontaneous abortions |
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Term
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Definition
non-disjunction is the failure of chromosomes to separate during mitosis or meiosis.
this is a major reason for chromosome abberations and spontaneous abortions |
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Term
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Definition
| Euploidy is when cells exhibit the normal multiple (human = 23) of chromosomes |
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Term
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Definition
| deviation from the normal multiples of chromosomes |
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Term
| What are the consequences of non-disjuntion during meiosis assuming fertilization? |
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Definition
| aneuploidy results from fertilization of egg after a non-disjunction event |
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Term
| When during meiosis can non-disjunction occur? |
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Definition
| Either at the first or second meiotic division, either of these will cause aneuploidy |
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Term
| What is 47 XXY and what are the characteristics? |
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Definition
47 XXY is known as Klinefelter's Syndrome and describes a non-disjunction event in the sex chromosomes resulting in trisomy.
Clinically patients with Klinefelter's show decreased sterility and in some cases hypogonadism or the development of breast tissue |
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Term
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Definition
Aggresive male syndrome
non-disjunction event in the sex chromosomes creating a trisomy
Clinically very little presentation with this trisomy, an increased incidence of learning disorders has been observed |
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Term
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Definition
Triple X syndrome
non-disjunction event during meiosis leading to trisomy in a female
clinically: Tend to be sub-clinical because lyonization keeps only one X expressed at a time. Rare cases include mental retardation, clusiness, hypolasia, etc |
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Term
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Definition
Turners Syndrome
non-disjunction event during meisosis leading to a sex chromosome monosomy
clinically: distinct physical appearance including short stature, webbed neck, low hairline, swelling, broad chest, low set ears. Also results in sterility due to non-functioning ovaries, no external genetalia. Aortic constriction that has to be surgically repaired |
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Term
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Definition
Patau Syndrome
autosomal non-disjunction event leading to trisomy at chromosome 13
clinically: distinct physical appearance including polydactyl. Damage to nervous system, cardiac system, urogenital system. |
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Term
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Definition
Edwards Syndrome (trisomy E)
autosomal non-disjunction event during meiosis
clincally causes many organ system deformations. Classically seen with overlapping fingers |
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Term
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Definition
Down syndrome
autosomal non-disjunction event during meiosis
clinically: distinctive physical presentation, typically seen with impaired cognitive function |
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Term
| Why is their no clinically defined monosomy OY? |
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Definition
| X chromosome necessary for life |
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Term
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Definition
| A structural abnormality with the chromosome. Generally result in mental retardation, heart defects, and facial abnormalities |
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Term
| What is the name of the syndrome associated with a microdeletion of 15q1-13? |
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Definition
Depends on whether it is a paternal or maternal deletion
paternal results in Prader-Willis Syndrome: mental retardation, hyperphagia, hypogonadism
Maternal: Angelman syndrome. Mental retardation, seizures, ataxic movements. |
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Term
| What is a balanced reciprocal translocation? |
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Definition
| this is an exchange of genetic material between two chromosomes. Balanced meaning the exchange is with equal genetic material (no genetic material missing or added on either side). And reciprocal because both chromosomes recieve genetic information |
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Term
| What is a Robertsonian translocation? |
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Definition
| A unreciprocal translocation of DNA. Meaning only one chromosome recieves viable genetic material. Typically happens with acrocentric chromosomes, the two q arms come together to form one chromosome |
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Term
| What are the consequences of fertilization after a balanced reciprocal translocation? |
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Definition
| Depends on the homologous pairing. Can result in fairly normal offspring or can be lethal. This is dependent on if the haploid gamete cell has the full genetic sequence (irrelevant if translocated or not) |
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Term
| What is an acrocentric chromosome? |
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Definition
| An acrocentric chromosome is a chromosome with a very small p arm. These chromosomes (13, 14, 15, 21, 22) have potential for Robertsonian translocations |
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Term
| What disease results in the translocation of a third 21 chromosome to chromosome 14? |
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Definition
| Downs syndrome. This is technically speaking a trisomy of 21 |
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Term
| What is the name of the disease caused by a disruption of the FMR1 gene? |
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Definition
Martin-Bell syndrome
FMR1 gene necessary for proper neural development.
This is caused by a small segment of genetic code being repeated on a fragile site Xq27.3. Since it is an X chromosome this disease is far more likely in men. |
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