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Exam 1 Study GuideChapters 1-5

Chapter 1: Introduction to Genetics

I. What is Genetics?a. Study of _________________ and _______________________.

II. Branches of Genetics

Transmission Molecular PopulationTransmission of genes

from generation to generation

Mechanisms underlying storage, replication, and

expression of genes

Explores evolution

Focuses on the ________________

Focuses on the _____________

Focuses on the ____________

III. What is DNA?a. What is it made of? (3 main components).

i. _________________________ii. _________________________

iii. _________________________

b. DNA is a double-stranded nucleic acid polymer. What holds together the strands of nucleotides?

i. ____________________________________ii. How do the bases pair?

1. Adenines (A) base pair with ____________________.2. Guanines (G) base pair with ____________________.

IV. Flow of Genetic Information (Fill in the missing information).a. Write the central dogma:

b. Where is genetic information stored? i. _____________________________________________________

V. What is RNA?a. What are the main differences between DNA and RNA?

i. _______________________________________ii. _______________________________________

iii. _______________________________________

VI. What is a Gene? (Has multiple definitions). a. A gene can be defined as:


i. A discreet unit of inheritance.ii. A specific DNA region located on a chromosome.

iii. A sequence of nucleotides that encodes information for a functional product.

b. What is a chromosome?i. DNA + proteins = _____________________

ii. How are chromosomes organized in:1. Eukaryotes? ___________________________________

a. Where are they found? ____________________

2. Prokaryotes? __________________________________

a. Where are they found? ____________________

iii. Each gene has a specific location on a chromosome called a __________.

VII. What is an allele?a. One of multiple _____________________ of a gene.

i. Individuals have _____ alleles for each gene. Where does each copy come from?

VIII. Genotype vs. Phenotypea. Genotype is the specific alleles an individual has.b. Phenotype is the individuals’ observable appearance.

i. TIP: Phenotype is the visual expression of genotype!

IX. Terminologya. Homozygote individuals have ________________ alleles for a gene.

i. EX: ______________b. Heterozygote individuals have ___________________ alleles for a gene.

i. EX: ______________

c. Dominant alleles are __________________ in heterozygotes.d. Recessive alleles are _______________________ in heterozygotes. e. Wild-type allele is the most commonly observed phenotype OR genotype.

f. What is the difference between recombination and mutation?i. Most mutations are _______________________.


Chapter 2: Chromosomes and Cellular Reproduction

I.

II. Prokaryotic Cell Reproductiona. Occurs through a process called ___________________________

i. Steps:1. Copy genetic material2. Separate genetic material3. Cell division

III. Eukaryotic Cell Reproductiona. Mitosis

i. Occurs with ____________________ cells

b. Meiosis i. Occurs with ____________________ cells

***These cells can also undergo mitosis

c. Diploid vs. Haploid i. Diploid cells have ______ copy/copies of each chromosome. ii. Haploid cells have _______ copy/copies of each chromosome.

iii. A pair of chromosomes are called _______________________________ 1. T/F: They carry the same linear sequence of genes.

Prokaryotes Eukaryotes


IV. Mitotic Cell Cycle

a. Practice problem:i. A cell in G1 has 4 chromosomes (2n = 4).

# of Chromosomes # of DNA moleculesS phase

G2 phaseMetaphaseAnaphase

Cytokinesis (in each daughter cell)


V. Meiotic Cell Cycle (2 parts)a. Meiosis I


b. Meiosis II


c. Practice problem:i. A cell in G1 has 6 chromosomes (2n = 6).

# of Chromosomes # of DNA moleculesS phase

Anaphase ICytokinesis I (each

cell)Anaphase II (each

cell)Cytokinesis II (each

cell)ii.

VI. Sources of Variation in Meiosisa. Recombination

i. Creates __________________________________ of alleles.1. This is due to synapsis and crossing over

ii. How is this different from mutation?

b. Independent Assortmenti. Homologous chromosomes line up randomly at the metaphase plateii. Chromosomes are sorted independently of each other

iii.

1. Possible number of combinations is: _________


VII. Movement of Sister Chromatids During Mitosisa. Which protein holds together the DNA molecules? ______________

i. Holds together from ______________ to ____________________

b. What protein allows sister chromatids to separate? _______________i. What stage does it act on? _______________

VIII. Movement of Sister Chromatids During Meiosis

a. Meiosis Ii. Which protein holds together the DNA molecules? ______________

1. Where on the chromosome is it acting?a. Homologs: ____________________b. Sister chromatids: ________________________

b. What protein allows sister chromatids to separate? _______________i. In meiosis I, where does it act? _____________________ii. In meosis II, where does it act? _____________________

1. What prevents sister chromatids from separating in meiosis I? a. ___________________________________

c.


Chapter 3: I. Genotype vs. Phenotype?

a. An organism inherits its __________________b. An organism does not inherit its ___________________________

II. Monohybrid Experiment****a. Follow only ____ characterb. Parents (P) are true breeders, meaning they are __________________________

for a trait.c. F1 offspring express only 1 of the P generation phenotypesd. F2 offspring expresses both P generation phenotypes in a

___________________ ratio.

III. Punnett Squares!a. True breeder, AA x AA

b. True breeder, AA x aa

c. Heterozygote, Aa x Aa

i. Law of segregation: 50% chance of allele A or a passing to any gamete


IV. What is a backcross?a. Cross F1 genotype with either one of the P parental genotypes (which we know

are truebreeders)

Lets cross F1 (Aa) x P (aa)

1. Genotypic ratio: ______________________2. Phenotypic ratio: _____________________

V. What is a testcross?a. Cross an unknown dominant genotype (AA or Aa?) with a homozygous recessive

genotype

VI. Rules of Probability a. Rule #1: Rule of Multiplication:

i. The probability that 2 or more events will occur together is the product of their individual probabilities

b. Rule #3: Rule of Addition: i. The probability that either 1 or 2 or more mutually exclusive events will

occur is the sum of their individual probabilities

ii. Once mastered, these rules will get you the same results as a Punnett square will!


VII. Dihybrid Cross***a. Crossed pea plants that differed in 2 characteristicsb. Led to Mendel’s 2nd law: ________________________________________

i. States that alleles at different loci separate independent of one another

c. Crossed two true breeder pea plants F1 progeny had 4 possible combinations of alleles

i. When the F2 generation was crossed, phenotypic ratio of: ____________________________

d. Tip for solving dihybrid crosses:i. Solve them as separate monohybrid crosses! ii. Use the multiplication rule to find the probability of the two crosses

occurring together

e. Let’s practice!i.

1. TIP: look at each gene as a separate monohybrid cross


ii. BE CAREFUL : make sure you’re paying attention to terminology genotype vs. phenotype

Chapter 4: Sex Determination and Sex-Linked Characteristics:

I. What are the differences between the sexes?a. The gametes produced!

i. Males produce _____________________ gametesii. Females produce ______________________ gametes

II. Why does sexual reproduction exist?a. To form _____________________ different from _______________________

i.

ii. Meiosis produces __________________ gametesiii. Fertilization produces _____________________ gametes

III. What is aneuploidy?a. How does it occur? __________________________________________________

i. What is this called? _________________________________

b. What are the different types of aneuploidy?i. Monosomy: ___________ii. Trisomy: ____________

IV. Types of Aneuploidya. Triplo-X Female

i. How many chromosomes? 1. Genotype: __________________________


ii. Clinical significance: __________________________________________

b. Kleinfeld’s Syndromei. How many chromosomes?

1. Genotype: __________________________ii. Clinical significance: __________________________________________

c. Turner’s Syndromei. How many chromosomes?


d. XYY Conditioni. How many chromosomes?


V. X-chromosome Inactivationa. Why does it occur?b. What is the inactivated chromosome called? ________________________c. What are tortoiseshell cats?

Chapter 5: Extensions and Modifications of Basic Principles

I. What is dominance?a. Dominance affects how genes are _____________________ expressed, not how

they are _______________________inherited

b. Types of dominancei. Complete dominance :

ii. Incomplete dominance:

iii. Co-dominance :


II. Gene Interactiona. So far, we have assumed that 2 genes at different loci act independently, but

what if they affect each other?i. Ex: dog fur

b. What is epistasis? ___________________________________________________

i. What is an epistatic gene? __________________________ii. What is a hydrostatic gene? _________________________

1. How can we tell the difference?

III. Cytoplasmic Inheritance?a. How many nucleotides do we have in the nuclear genome? _________________b. How many nucleotides do we have in the cytoplasm / mitochondria?

__________________________

i. Which parent passes on mitochondrial DNA?

c. Solving problems:REMEMBER: The phenotype of the offspring is determined by the genotype of the mother

i. PRACTICE:1. A father with the genotype S+S is crossed with a mother that has

the genotype SS. What are the genotypes and phenotypes of the F1 and F2 offspring?

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