science chapter 4.1/4.2- genetics
Terms
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- What are the 3 patterns of human inheritance
-
single gene with two alleles
single gene with multiple alleles
many genes that act together - what is an example of a trait controlled by a single gene with two alleles
- widow's peak (dominant over straight)
- what is an example of a trait controlled by a a single gene with multiple alleles
- Blood type:
- what is an example of a trait controlled by many genes?
-
Height
Skin color - How many alleles control the inheritance of blood type? what are they?
-
Three alleles:
type A written IA (codominant with B)
type B written IB (codominant with A)
Type O written i (recessive) - What are the possible blood types?
-
Type A- IAIA or IAi
Type B- IBIB or IBi
Type AB- IAIB
Type O- ii - How many pairs of chromosomes in each body cell?
- 23 pairs
- What is different about Sex chromosome pairs?
- The only chromosomes that do not always match: In a girl, they match (XX). In a boy, they do not (XY). The Y chromosome is smaller than the X
- What are sex linked genes
- Genes whose alleles are passed from parent to child on a sex chromosome (X or Y chromosome)
- what are sex linked traits?
- Traits controlled by sex linked genes.
- what is an example of a sex-linked trait?
- color blindness
- What is a carrier?
- A person who has one recessive allele for a trait and one dominant allele. They are a carrier because they do not have the trait but can pass it on to off-spring.
- Why are males more likely to have sex-link traits controlled by a recessive allele?
- Because females have two X chromosomes, a recessive allele on the X chrom. may be masked by a dominant allele on the other X chromosome, but a male only has one X chromosome and if it carries a recessive allele, the male will have the trait.
- Can both males and females be carriers of color blindness?
- No. Only females can be carriers of a sex-linked trait.
- If a child has blood type O and his parents are both AB, what can you tell about this child?
- He is adopted!
- What are the functions of the sex chromosomes?
- The sex chromosomes carry genes that determine whether a person is male or female. The also carry genes that determine other traits.
- Are a person's characteristics determined by genes alone?
- No. Many characteristics are determined by an interaction between genes and the environment.
- Give examples of characteristics affected by environment.
-
Height/weight-- affected by nutrition.
Ability to play a sport or musical instrument- requires physical traits and learning. - What is a genetic disorder?
- An abnormal condition that a person inherits through genes or chromosomes
- What are the two major causes of genetic disorders in humans?
-
Mutations in the DNA of genes.
Changes in the overall structure of chromosomes or number of chromosomes. - What is cystic fibrosis?
- A genetic disorder in which the body produces abnormally thick mucus in the lungs making it hare to breathe.
- What causes cystic fibrosis?
- a recessive allele on one chromosome that is a result of a mutation in which 3 bases are removed from a DNA molecule.
- What is Sickle-Cell Disease?
- A disesase that affect hemoglobin, a protein in red blood cells that carry oxygen. Sickle shaped red blood cells clog blood vessels and connot carry as much oxygen as other cells.
- What is hemophilia?
- A genetic disorder in which a person's blood clots very slowly or not at all.
- What causes hemophilia?
- A recessive allele on the X-chromosome. Because it is sex linked, it occurs more frequently in males.
- What causes Down Syndrome?
- A person's cells have an extra copy of chromosome 21. Instead of a pair of chromosomes, that person has 3 chromosomes. This occurs most often when chromosomes fail to separate properly during meiosis.
- What tool do geneticists use to trace the inheritance of traits in humans?
- A pedigree
- What is a pedigree?
- A chart or a family tree that tracks which members of a family have a particular trait.
- How are males and females represented in a pedigree?
- A male is a square, a female is a circle.
- What is a karyotype?
- A picture of all of the chromosomes in a cell.
- How are karyotypes used?
- To help diagnose genetic disorders.
- What can you tell from a karyotype?
- You can tell if a person has the correct number of chromosomes.
- What do genetic counselors do? What tools do they use?
- They helps couples understand their chances of having a child with a particular disorder. They use Punnett squares, pedigree charts and karyotypes.
- How are people with genetic disorders helped?
- Through medical care, education, job training and other methods.
- How is cystic fibrosis treated?
- With physical therapy to help remove mucus from the lungs.
- How is sickle-cell disease treated?
- People take folic acid to help their bodies make red blood cells
- A ____________gene is masked if it is paired with a dominant gene.
- Recessive
- Of the two sex chromosomes, which has the fewer genes?
- The Y chromosome
- A female has two _______________.
- X chromosomes
- The traits that are visible in an organism determine its _____________.
- phenotype
- A sex cell is called a _____________.
- Gamete