7C Genotypes and Phenotypes

Question 1

1. In terms of genetic terminology, explain a trait

Answer 1

Trait - any characteristic that can be passed from parent to offspring

Question 2

2. In terms of genetic terminology, explain heredity

Answer 2

Heredity - passing of traits from parent to offspring

Question 3

3. In terms of genetic terminology, explain genetics

Answer 3

Genetics - study of heredity

Question 4

4. In terms of genetic terminology, explain genotype

Answer 4

Genotype – is our genetic makeup, we cannot see our genes, Genotype is determined by how the parent’s alleles combine during reproduction.

Question 5

5. In terms of genetic terminology, explain alleles

Answer 5

Alleles – are different forms of a gene

Question 6

6. Where do the copy of our genes comes from?

Answer 6

Copy of our genes are one from our mother and one from our father

Question 7

7. Are all alleles expressed equally?

Answer 7

Not all alleles of a particular gene are expressed equally. In most cases one allele will be dominant and will ‘mask’ the expression of the other allele in an organism’s phenotype. Dominant alleles are written using capital letters, whereas recessive alleles are written with lowercase letters.

Question 8

8. If a mother has the aa genotype and the father has the AA genotype, how many types of genotypes are possible?

Answer 8

One, Aa

Question 9

9. If each parent has the Aa genotype, how many types of genotypes are possible for their offspring?

Answer 9

Three, AA, Aa or aa

Question 10

10. What is the different between a genotype and phenotype?

Answer 10

Genotype if the genetic code of the organism ie. RR, Rr, rr, phenotype if the physical features ie. Red, white

Question 11

11. How is a phenotype determined?

Answer 11

Phenotypes is determined by the alleles of the genes and if there are dominant alleles present

Question 12

12. Explain how to use a Punnett square?

Answer 12

The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype.

Question 13

13. For alleles, what is the difference between dominant and a recessive gene?

Answer 13

• Dominant - stronger of two genes expressed in the hybrid; represented by a capital letter (R), dominant allele the variant of a gene that masks the effect of a recessive allele of the same gene on a homologous chromosome always be expressed even if the individual only has one copy of that allele
• Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r), recessive allele the variant of a gene that is masked by a dominant allele on a homologous chromosome only be expressed if the individual has two copies of that allele carrier an organism that has inherited a copy of a recessive allele for a genetic trait but does not display the trait due to it being masked by the presence of a dominant allele

Question 14

14. In terms of genotypes, what is the difference between homozygous genotype and heterozygous genotypes?

Answer 14

• Homozygous genotype - allele combination involving 2 dominant or 2 recessive alleles (e.g. RR or rr); having identical alleles for the same gene on homologous chromosomes, also called pure
• Heterozygous genotype - allele combination of one dominant and one recessive

Question 15

15. Explain complete dominance?

Answer 15

Complete dominance is a pattern of dominance where only the dominant allele from the genotype of a heterozygous individual is expressed in the phenotype of that organism, Capital letters are used to denote the dominant allele

Question 16

16. Explain incomplete dominance?

Answer 16

Incomplete dominance is a pattern of dominance where neither allele from the genotype of a heterozygous individual is dominant and both are expressed in an intermediate phenotype.

Question 17

17. Explain codominance?

Answer 17

The phenotype of both homozygotes are expressed equally in the heterozygote, so mixing a red flower and a white flower, will have red leaves and white leaves

Question 18

18. What may have an effect of phenotypes? Ie for example with identical twins are they always the same why not?

Answer 18

The environment can have an impact, no identical twins are not always the same the environment can affect them, ie is one has depression and the other not, it is due to the exposure to different environments

Question 19

19. What are the sex linked genes?

Answer 19

The sex-linked genes are genes that are located on a sex chromosome
X-linked traits a trait controlled by a gene that is located on the X chromosome
Y-linked traits a trait controlled by a gene that is located on the Y chromosome

Question 20

20. Where do males get their X chromosomes from?

Answer 20

From their mothers

Question 21

21. Where do females get their X chromosomes from?

Answer 21

From their mothers and fathers

Question 22

22. Who is the X linked recessive gene more common in?

Answer 22

More common in males

Question 23

23. Can X linked recessive skip a generation?

Answer 23

Yes

Question 24

24. Are X linked dominant as common as X linked recessive?

Answer 24

No

Question 25

25. Can X linked dominant skip a generation?

Answer 25

No

Question 26

26. For females who have an X linked dominant, do they always pass this onto their off spring.

Answer 26

Yes

Question 27

27. What is Y linked inheritance usually a determinant of

Answer 27

The sex and fertility

Question 28

28. Do the incomplete and codominance worksheet questions

Answer 28

Do the incomplete and codominance worksheet questions