Flashcards in Unit 5 Study Guide Deck (26):
Differentiate between genotype and phenotype.
Genotype is an organism’s genetic make-up for a trait and the phenotype is the physical trait that can be seen.
What is the Law of Segregation?
Mendel’s Law of Segregation states that alleles on homologous chromosomes move independently of one another.
What is the Law of Independent Assortment?
Mendel’s Law of Independent Assortment says that each pair of homologous chromosomes moves to the metaphase plate during Metaphase 1 independently and the placement of the chromosome on the metaphase plate is random.
Explain Incomplete Dominance and give an example.
Incomplete dominance (has a heterozygous phenotype)is when information from both alleles is expressed in the cell and neither phenotype is completely penetrant. (Ex. Red + White = Pink)
Explain Codominance and give an example
Codominance is when both alleles are expressed in the cell and equally present in the phenotype. (Ex. black and white fur)
What is a pedigree? What do squares represent? Circles? Shaded shapes?
A pedigree is a family history of trait occurrence in chart form. It helps to tell past and future occurrences of a trait. Squares represent males and circles represent females. Fully shaded shapes mean that the person has the trait and half shaded shapes mean that person is a carrier.
What is a recessive disorder? Give an example and symptoms.
A recessive disorder can only occur in the homozygous recessive state. An example is cystic fibrosis which creates a faulty Chloride ion protein carrier on cell membranes in the lungs. This causes fluid to build up in the lungs.
What is a dominant disorder? Give an example and symptoms.
A dominant disorder only needs one allele for it to be expressed. One example of a dominant disorder is Achondroplasia. The people with this disorder are very short.
What is a gene? Locus? Genome?
A gene is a unit of hereditary information in the form of a DNA sequence of nucleotides. A locus is the location of a gene on a chromosome. A genome is an organism’s entire genetic make-up.
What is asexual reproduction? Give some benefits and risks.
Asexual reproduction is when the parent produces genetic clones of itself. The benefit is that it can happen very quickly. The risk is every organism is exactly the same.
What is sexual reproduction? Give some benefits and risks.
Sexual reproduction is when 2 parents contribute DNA. The benefit is it creates variation. The risk is it takes 2 to reproduce and it takes more time.
What is a karyotype?
A karyotype is a picture of the chromosomes
What are somatic cells? What are germ cells? How do they differ?
Somatic cells are body cells. Germ cells (gametes) are sex cells. Somatic cells have 46 chromosomes while germ cells only have 23.
What 3 things must occur for meiosis to happen correctly?
The 3 things that must occur for meiosis to happen correctly are 1 DNA replication and 2 cell divisions.
List 3 major differences between meiosis and mitosis.
The 3 major differences between meiosis and mitosis are the crossover in Prophase 1, chromosome pairs independently sort in Metaphase 1, and the sister chromatids separate in Anaphase 1.
What is crossover and when does it occur?
Crossover is genetic swapping between homologous chromosomes. It creates variation and occurs in Prophase 1.
What is a chiasmata?
A chiasmata is where the chromosomes physically overlap making an “x”.
What are linked genes?
Linked genes describes genes found on the Autosomes (1-22). These are usually inherited as a linked unit as they are found on the same chromosome. These genes are not independently assorted by rather they are inherited as a package.
What are sex-linked genes?
Sex-linked genes are genes found on the sex chromosomes. 95% of the time it refers to the X chromosome.
Why are males more likely to have a sex-linked genes disorder? Give an example.
Males are more likely to have a sex-linked disorder because they only have one X chromosome and if the X they have contains the recessive allele with the disease there is not another X to cancel it out. Females are less likely to have these disorders because they have two Xs and both would have to have the disorder for them to have it. Color blindness and hemophilia are both sex-linked disorders.
How do sex-linked genetic disorders appear on a pedigree?
On pedigrees, sex-linked genetic disorders appear to mainly affect males.
What is aneuploidy? Aneuploidy is the result of?
Aneuploidy is an abnormal number of chromosomes. This occurs because of non-disjunction (failure to separate during Anaphase).
Chromosome structure errors occur as a result of what?
Chromosome structure errors occur as a result of faulty crossover.
Define deletion, duplication, inversion, and translocation in reference to chromosome structure errors.
Deletion - A chromosome segment is missing. It got stuck on the other homologous chromosome during crossover. Duplication - A chromosome segment was copied twice (2 genes on one chromosome. It is missing from the other homologous chromosome.) Inversion - A chromosomal segment is backwards. It was inverted backwards during crossover. Translocation - A chromosomal segment is attached to a different autosome. It accidentally broke loose and ended up on another chromosome.
What is Down's Syndrome? How would it appear on a karyotype?
Down’s Syndrome affects about 1 in 700 births, these individuals possess an extra 21 autosome, and is mainly the result of women of advanced age having babies. On a karyotype, they would appear to have an extra 21 autosome (trisomy 21).