1. Worksheet: Unit 3 Review
BIOLOGY
Worksheet: Unit 3 Review

2. Define the following terms:
Homozygous-
heterozygous -
true breeding-
genotype-
phenotype-
non-disjunction-
co-dominance-
incomplete dominance-
linked genes-
genetic engineering-
cloning-

3. Homozygous- two of the same allele (i.e. EE or ee)

4. Heterozygous- Two different alleles (i.e. Ee or Ss)

5. True-breeding- Means the same thing as pure-bred
True-breeding- Means the same thing as pure-bred. Will always produce the same offspring.

6. Genotype- The “letter” combination
Genotype- The “letter” combination. Describes the two alleles an organism has (i.e. EE, Ee, ee)

7. Phenotype- The physical characteristic that results from a gene (i. e
Phenotype- The physical characteristic that results from a gene (i.e. Tall or short, Red or white)

8. Non-disjunction- When chromosomes do not separate during meiosis
Non-disjunction- When chromosomes do not separate during meiosis. Results in gametes with extra or too few chromosomes
Example: would result in Down Syndrome, Klinefelters Syndrome, Turner’s Syndrome)

9. Co-dominance- Both alleles are dominant and both expressed in offspring.
(i.e. Red and White hair are dominant in cattle. A purebred red is crossed with a purebred white cow and results in a cow that is roan in color- has both red and white hair)

10. Incomplete dominance- Neither allele is dominant.
red flower crossed with white flower and produces pink flowers in offspring

11. Linked genes- Genes that are located on the same chromsome
Linked genes- Genes that are located on the same chromsome. Usually inherited together- they’re “linked”

12. Genetic engineering- changing of an organisms DNA to give new trait

13. Cloning- creating a genetically identical copy of gene or of an organism

14. What do you call the process where two gametes fuse?
Fertilization

15. 3. What is the name of the cell that is formed as a result of this fusion?
Zygote

16. What is crossing-over (what process does it occur in, and what is the result of this process)?
When chromosomes cross over each other during meiosis and exchange bits and pieces of themselves

17. 5. Describe the process of DNA replication
5. Describe the process of DNA replication. (where does it occur and what is the result)
DNA making copy of DNA. Occurs in nucleus of cell. Requires certain enzymes to catalyze reaction.

18. DNA RNA 6. Complete the chart below comparing DNA and RNA: Deoxyribose
Type of sugar
Deoxyribose
Ribose
Nitrogen base
A,T,C,G
A,U,C,G
Complimentary bases
A-T C-G
A-U C-G
Double or Single stranded?
Double
Single

19. 7. Blood type is determined by multiple alleles
7. Blood type is determined by multiple alleles. Complete the chart below showing possible genotypes and phenotypes of blood type (page 205)
Phenotype
Genotype
Type A
IAIA, IAi
Type B
IBIB, IBi
Type AB
IAIB
Type O ii

20. 8. A human karotype shows 22 pairs of autosomes, and one pair of sex chromosomes.

21. 9. A male has the genotype XY and a female has the genotype XX

22. 10.In the process of transcription a DNA sequence reads CATTGA, what would the complementary mRNA strand that would read?
CATTGA
GUAACU

23. 11. The genes on DNA contain instructions to assemble proteins

24. 12.The monomers of proteins are amino acids

25. 13. Three nitrogen bases make up a codon for an amino acid.

26. 14.State Mendel’s principles of genetics.
a. What is the Principle of Dominance?
Some alleles are dominant and some are recessive

27. b. What is the Law of Independence Assortment?
allele pairs separate independently of each other during meiosis

28. 15. Be able to use the genetic code chart
15.Be able to use the genetic code chart. What are the amino acids coded for with the following codons?
a. UUU-
b. UUC-
c. ACG-
d. CCU-
e. AUU-
f. AAA-
g. GUC-
h. GCC-

29. 15. Be able to use the genetic code chart
15.Be able to use the genetic code chart. What are the amino acids coded for with the following codons?
a. UUU- Phe
b. UUC- Phe
c. ACG- Thr
d. CCU- Pro
e. AUU- Ile
f. AAA- Lys
g. GUC- Val
h. GCC- Ala

30. 16.Summarize the process of translation; (where does it occur and what is the result. Include the three types of RNA involved)
RNA making Proteins. Occurs in the cytoplasm on the ribosomes. Involves all three types of RNA (mRNA, tRNA, and rRNA)

31. 17. What did Mendel call the “factors” that determine traits?
Genes

32. 18.What organisms do Mendel’s principles apply to?
All living things

33. 19.What causes mutations in DNA?
a. Are all genetic mutations expressed? Explain
No. May not affect phenotype. May not change protein produced. May occur in non-coding part of DNA

34. b. What created oil-eating bacteria?
Induced mutations (radiation)

35. 20.What is the purpose of Punnett squares?
A tool to predict the possible offspring of a genetic cross

36. State the phenotypic ratio of a heterozygous dihybrid cross?
9:3:3:1

37. 22. Why would a scientist or breeder use selective breeding?
To try and combine certain traits in offspring to produce desired results

38. 23. What is inbreeding and how does it occur?
Inbreeding is when two closely related organisms are crossed. Increases the chances that recessive alleles will combine in offspring

39. 24. Skin color in humans is a result of Polygenic inheritance.

40. 25. What are the possible gametes produced by the parent genotypes below?
a. RrYy- RY, Ry, rY, ry
b. rrYY- rY only
c. SSDD- SD only

41. 26. Colorblindness is a sex-linked trait
26. Colorblindness is a sex-linked trait. Why do males exhibit colorblindness more than females?
Because the genes are carried on the X chromosome and males only have one X chromosome. If they have the recessive allele they will have the disorder

42. MITOSIS MEIOSIS 2 4 Diploid Haploid Asexual Sexual Body cells
27. Complete the following table comparing Mitosis to Meiosis:
MITOSIS
MEIOSIS
Number of cells produced 2 4
Haploid or diploid cells produced
Diploid
Haploid
Involved in asexual or sexual reproduction
Asexual
Sexual
Results in body cells or sex cells
Body cells
Sex cells
Number of divisions involved (one or two)
One
Two

43. 28. Complete the chart below comparing the process of Replication, Transcription and Translation.
Where does it occur?
Nucleus
Cytoplasm
___ making ___
DNA making DNA
DNA making RNA
RNA making Proteins
What molecules are involved in the process? (DNA, mRNA, tRNA, rRNA)
DNA
DNA and RNA (mRNA, tRNA, rRNA)
RNA
(mRNA, tRNA, rRNA)