Genetics Flashcards
Examples of Chromosomal Abnormalities
- Alteration of chromosome number:
- Polyploidy—complete sets of extra chromosomes
-
Aneuploid—chromosome number not 23—trisomy (trisomy 21 = Downs Syndrome)
- nondisjunction is common cause- occurs during meiosis when there is failure to separate chromosomes ( meiosis I) or sister-chromatids (meiosis II)
- Alteration in Chromosome Structure:
- Inversions
- Deletions
- Translocations
Single-gene disorders
- caused by mutations in individual genes
- may be present on one or both alleles
_____ follows mitosis, forming two daughter or progeny cells
Cytokinesis
Which of the following statements is true about an individual who is a carrier for the cystic fibrosis (CF) gene?
- Homozygous; suffers from CF
- Homozygous; does not suffer from CF
- Heterozygous; suffers from CF
- Heterozygous; does not suffer from CF
Heterozygous; does not suffer from CF
If an individual is a carrier, they are heterozygous for the recessive trait (in this case, CF), but they do not display the trait (because the trait is recessive)
Mendels pundentt square
dominant and recessive alleles; homozygous and heterozygous
¼ = A ½ = Aa ¼ = a
Mendel’s first law
Mendel’s first law, the principle of segregation, states that the two members of a gene pair (alleles) segregate (separate) from each other in the formation of gametes; half of the gametes carry one allele, and the other half carry the other allele
involves the division of the nuclear material of a cell
Mitosis
When in cell cycle does DNA replication happen?
S phase of cell cycle maintains the genomic information using DNA polymerase
chromosome number that is not 23
aneuploid
an example is trisomy, trisome 21 is downs syndrome, a common cause is nondisjunction
two genes together might create a new phenotype
collaborative
Contains the basic genetic information, and its expression as proteins determines the various functions of that cell
DNA structure base A, T, G, C + sugar and phosphate
Meiosis I
- Homologous chromosomes line up in the middle of the cell.
- Homologous chromosomes separate to opposite sides of the cell.
- Random shuffling of maternal and paternal chromosomes occurs.
- Crossing over or exchange between homologous segments of the sister-chromatids that make up each homologous chromosome occurs.
- Random shuffling and crossing over result in genetic recombination that ensures that genetic information in the offspring is unique.
- Result is two cells that contain 23 individual chromosomes. Each of these chromosomes has two copies or is composed of sister-chromatids.
Genetic exchange of maternal and paternal information occurs during _____ through recombination
Meiosis
many genes can affect one trait
polygenic
What is semi-conservative replication?
when replicating each DNA molecule contains one original strand and one newly synthesized strand, it ensures that any mistakes or mutations introduced during the DNA replication process can be fixed
The diploid nautre of somatic cells is maintained by _____ while the haploid number in the gametes is obtained through a process called _____
Mitosis, Meiosis
Meiosis II
The result of meiosis I is two cells that each contain individual chromosomes that have been copied (sister-chromatids). There is no duplication of genetic material in between meiosis I and II. Meiosis II will involve the further separation of each of those sister-chromatids to generate four cells each with one copy of each of the 23 homologous chromosomes. Thus, from the original diploid parent cell there are now four haploid cells that contain one copy of each chromosome. Meiosis is the process that produces the gametes—sperm and ovum—that will fuse during fertilization to form the zygote
Identifies mutations associated with disease, identifies markers of disease or predictors of disease risk or likelihodd of response to certain drug treatments
Human Genome Project
one gene might depend on another
complementary
If an unaffected mother carries one normal and one mutant allele on her X chromosome, what are the chances that she will transmit the defective gene to her sons?
- 25%
- 50%
- 75%
- 100%
50%
Because a son receives the X sex chromosome from his mother (who has one normal and one mutant allele), there is a 50% chance that the mutant allele will be inherited.