Study Guide Genetics DOK 5
Name:
Key
Block: ___________
Define the following terms:
1. Chromosome-organized structures of DNA that stay inside the nucleus
2. DNA-Deoxyribonucleic Acid-the molecule that contains the code for traits
3. Gene-sections of chromosomes that code for specific traits
4. Dominant Trait-characteristics that are expressed if present in the genotype
5. Recessive Trait-characteristics that are masked by dominant traits unless there are two of them
6. Environmental Trait-characteristics influenced by where and how an organism lives
7. Inherited Trait-characteristics that are genetically passed from parent to offspring
8. Genotype-an organism’s inherited alleles (actual DNA code)
9. Phenotype-an organism’s inherited appearance (the way the DNA code makes the organism
look)
10. Heterozygous-Two different alleles for a trait. Ex. Bb
11. Homozygous-An allele is repeated (BB, bb)
12. Alleles-options or choices for specific genes
13. Probability-the likelihood, or chance, of an event happening
Answer the following questions:
14. What important contribution did Gregor Mendal make to our body of knowledge about
genetics?
Studied pea plants and discovered dominant and recessive traits
15. What important contribution did Rosalind Franklin make to our body of knowledge about
genetics?
Took a famous photo (Photo 51) of DNA and discovered that DNA has a spiral shape
16. What important contribution did James Watson and Francis Crick make to our body of
knowledge about genetics?
Discovered that DNA is a double helix
17. What is the shape of DNA? spiral
Study Guide Genetics DOK 5
18. What is the structure of DNA? Draw and describe. Double helix
The structure of DNA is two phosphate sugar chains held together by nitrogen bases
19. What makes up the backbone of DNA? (known as the side poles of the ladder)
Sugar and phosphates
20. What makes up the inside of the DNA molecule? (steps or rungs of the ladder)
Nitrogen bases
21. How do the bases pair together?
AT, and CG
22. How many chromosomes are in human body cells? 46
23. How many chromosomes are in human gametes (reproductive cells)? 23
24. Complete the complementary strand for the strand of DNA given.
A
T
T
A
C
G
A
T
G
C
C
G
C
G
T
A
T
A
A
T
G
C
25. Explain the difference between inherited and environmental traits.
Inherited traits are passed from parent to offspring and are a part of an organism’s genetic
makeup. Environmental traits are a result of an organism’s environment.
26. Give two examples of inherited traits.
Skin color, height, tongue rolling, and long second toe
27. Give two examples of environmental traits.
Favorite music, dyeing hair, choice of clothing style, language spoken
28. Why do identical twins have the same DNA and not the same personality?
Personality is not a result of DNA (inherited traits), but environmental ones instead.
29. What is the relationship between chromosomes, DNA, and genes?
Chromosomes are coiled structures of DNA that have genes on them.
30. How do genes and alleles relate to each other? Give one example.
Alleles are a specific choice for a gene. Ex. Gene=handedness, Alleles=right or left
Study Guide Genetics DOK 5
31. What is the difference between dominant and recessive traits?
Dominant traits are always expressed if they are present. Recessive traits are only expressed if
there is NO DOMINANT trait.
32. What is the relationship between genotypes and phenotypes?
Genotype is an organism’s genetic makeup. Phenotype is what those genes look like on the
organism.
33. What is homozygous? Give an example using any letter. (There are two types)
Homozygous means that an allele (the letters) are repeated. (BB, bb)
34. What is heterozygous? Give an example using any letter.
Heterozygous means that there are two different alleles present. Bb
35. State the goal of mitosis. To create body cells for growth and repair.
36. State the goal of meiosis. To create gametes (sex cells) for sexual reproduction.
37. Using the Venn diagram below, note the similarities and differences between mitosis and
meiosis.
Mitosis
Meiosis
Both
1.
2.
3.
4.
5.
Body cells for growth
and repair
46 chromosomes in
original cell and each
of the daughter cells
Asexual reproduction
Produce identical
cells
Makes 2 daughter
cells
-Both creates new
cells
1.
2.
-DNA replication
happens once
3.
-begins with 46
chromosomes
4.
5.
Makes gametes
for sexual
reproduction
46
chromosomes in
original cell and
23 in each of
the daughter
cells
Makes sex cells
for sexual
reproduction
Produces cells
with half the
DNA
Makes four
daughter cells
Study Guide Genetics DOK 5
38. Given the genotype Bb (brown is dominant and white is recessive), what is the phenotype?
brown
39. Given the phenotype white (which is recessive and purple is dominant) what is the genotype?
pp
Study Guide Genetics DOK 5
40. What are the genotypes of the parents for this Punnett square cross?
d
41.
d the.
D
D
Dd
Dd
Dd
Dd
42. Complete the following Punnett squares.
Square 1
Square 2
Rabbit fur
B=brown
b=white
B
_______
B
____
____
B
____
____
BB
Flower color
P=purple
p=white
b
_______
Bb
BB
Bb
p
____
____
p
____
____
P
_______
P
_______
Pp
Pp
Pp
Pp
Genotypic Ratio:
Genotypic Ratio:
BB: 50% Bb: 50% bb: 0%
PP: 0% Pp: 100% pp: 0%
Phenotypic Ratio:
Phenotypic Ratio:
Brown: 100% white: 0%
Purple: 100% white: 0%
Study Guide Genetics DOK 5
43. Determine the genotype of the parents using the following Punnett square.
R
R
r
RR
Rr
Genotypic Ratio:
RR: 25% Rr: 50% rr: 25%
Phenotypic Ratio:
r
rr
Rr
44. Label the picture below.
DNA
Gene
Chromosome
Round: 75% square: 25%
Study Guide Genetics DOK 5
45. Label the picture below.
Nucleus
Chromosome
Gene
Cell
DNA
46. The Green family has four daughters. What is the probability their next child will also be a girl?
50%
47. If a typical human body cell has 46 chromosomes, meiosis will produce sex cells with how many
chromosomes? 23
48. If a typical canine (dog) gamete has 39 chromosomes, how many chromosomes will be in the
body cells? 78