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Pathophysiology
Ch 4 - Genes and Genetic Diseases
| Question | Answer |
|---|---|
| What is genetics? | The study of biologic heredity |
| What is a gene? | The basic unit of heredity |
| What is a genome? | DNA representing all of the genes for a given species |
| What are the components of DNA? | A pentose sugar (deoxyribose), a phosphate molecule, and four types of nitrogenous bases. |
| What are nitrogenous bases? | nucleoproteins created from amino acids |
| What are the four nitrogenous bases? | Adenine, Guanine, Cytosine, Thymine |
| Which of the nitrogenous bases are purines? | Adenine and Guanine |
| Which of the nitrogenous bases are pyramidines? | Cytosine and Thymine |
| Which of the nitrogenous bases have a double ring structure? | Purines (A and G) |
| Which of the nitrogenous bases have a single ring structure? | Pyramidines (C and T) |
| DNA has what type of structure? | An antiparallel structure |
| Which nitrogenous bases pair with each other and how many hydrogen bonds are involved in each pair? | A pairs with T (2 hydrogen bonds) C pairs with G (3 hydrogen bonds) |
| What are proteins made of? | Amino acids |
| How many amino acids are there? | 20 |
| How does DNA replication work? | DNA strand untwists and unzips. A single strand acts as a template. DNA polymerase adds the matching base pair to the template strand and proof reads. |
| Describe the process of transcription, what it results in and where it occurs. | RNA is synthesized from the DNA template by RNA polymerase. Results in the formation of mRNA. Occurs in the nucleus. mRNA then leaves the nucleus and moves into the cytoplasm. |
| What is translation? | Process by which RNA directs the synthesis of a polypeptide via interaction with transfer RNA |
| Where is the site of protein sythesis? | The Ribosome |
| How does tRNA interact with mRNA? | tRNA contains a sequence of nucleotides (anticodons)complementary to the triad of nucleotides on the mRNA strand (codons). Codons paired with anticodons by the ribosome which moves along the RNA strand translating it into a polypeptide chain |
| What is a chromosome and what is it composed of? | A chromosome is a temporary but consistent state of DNA. It is composed of two sister chromatids. |
| How many chromosomes do somatic cells contain and what kind of cells are they. | 46 chromosomes (23 pairs). diploid cells |
| How many chromosomes do gametes contain and what kind of cells are they? | 23 chromosomes. haploid cells |
| What is meiosis? | Formation of a haploid cell from a diploid cell. |
| What are autosomes? | The first 22 of the 23 pairs of chromosomes. The two members are virtually identical and are thus said to be homologous. |
| What are sex chromosomes? | The remaining pair of chromosomes. In females it is a homologous pair (xx) and in mails it is a nonhomologous pair (xy) |
| What are the pieces of the chomosome structure? | Short arm Long arm Centromere- regioun of attachment for sister chromatids Telomere- region containing multiple base pairs. shortens with each cell division. |
| What is a karyotype? | An ordered display of chromosomes. |
| What is a mutation? | Any inherited alteration of genetic material |
| Are mutations in somatic cells transmitted to offspring? | No |
| Are mutations in gametes transmitted to offspring? | Yes |
| What is a point mutation? | A single nucleotide base-pair change in DNA |
| What is a mutagen? | An agent known to increase the frequency of mutations |
| What are some examples of a mutagen? | radiation and chemicals |
| What is a silent muation? | A change in DNA sequence that does not change the amino acid sequence of a gene. |
| What is a missense mutation? | A type of mutation that results in a single amino acid change in the translated gene product. |
| What is a nonsense mutation. | A type of mutation in which an mRNA stop codon is produced or removed. |
| What happens in a nonsense mutation if a stop codon is produced? | The protein sequence is terminated prematurely |
| What happens in a nonsense mutation is a stop codon is removed? | An elonged protein sequence is created |
| What is a frameshift mutation? | An alteration of DNA in which an addition or deletion of a base pair occurs. Results in a change in the entire reading frame. |
| What are gain of function mutations associated with? | Autosomal dominant disorders. Cause production of new protein product or overexpression/inappropriate expression of protein product. |
| What are loss of function mutation associated with? | Associated with recessive disorders. Loss of 50% of the protein product. This may or may not be adequate for normal function. |
| What are euploid cells? | Cells that have a multiple of the normal number of chromosomes. |
| What is a polyploid cell? | A euploid cell that has more than the diploid number. examples= triploidy and tetraploidy |
| What is disjunction? | Normla separation of chromosomes during cell division |
| What is nondisjunction? | Failure of homologous chromosomes or sister chromatids to separate normally during meiosis or mitosis. Usually the cause of aneuploidy. |
| What is aneuploidy? | A somatic cell that does not contain a multiple of 23 chromosomes. |
| Is it better to have more genetic informaiton or less? | More. Mutations with less often do not survive although there are still consequences to having more genetic material. |
| What are some physical characteristics of down's syndrome? | mental retardation, low nasal bridge, epicanthal folds, protrouding tonge, poor muscle tone. |
| What is partial trisomy? | Only an extra portion of a chromosome is present in each cell. |
| What is a chromosome mosaic? | Trisomies occuring only in some cells of the body. |
| What is trisomy x? | A female that has three x chromosomes. termed "metafemale". Symptoms may include sterility, menstrual irregularity, and/or mental retardation. |
| What is turner syndrome? | Females having only one x chromosome. Characteristics include absence of ovaries, shor stature, webbing of neck, underdeveloped breasts. |
| What is Klinefelter syndrome? | Individuals wtih at least two x's and one y chromosome. Characteristics include male appearance, development of female like breasts, long limbs, small testes, and sparse body hair. |
| What is a deletion? | Loss of a sequence of DNA from a chromosome |
| What is an inversion? | Chromosomal rearrangement in which a segment of a chromosome is reversed end to end. |
| What is a translocation? | Transfer of one chromosome segment to another |
| What is a ring chromosome? | Telomere of each chromosome arm has been deleted and the broken arms have joined |
| What causes Cri du chat sydrome | Deletion of short arm on chromosome 5. |
Created by:
MEPN 2013
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