Biology
Unit 2 - Genetics
Williams
Name _________________________________________________ Date: ________________________ Hr: _____________
Exam 2 – Study Guide
Meiosis, DNA replication, RNA transcription & translation
Label the following stages of meiosis:
(Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II,
Telophase II)
Anaphase I
Anaphase II
Prophase I
Metaphase I
Metaphase II
Telophase I
Prophase II
When does crossing over occur?
Prophase I
Telophase II
Biology
Unit 2 - Genetics
Williams
Name _________________________________________________ Date: ________________________ Hr: _____________
What is cytokinesis?
When telophase is complete, cytoplasm is divided and the original cell is divided.
What two phases occur before prophase I? What happens in those phases?
G1 phase- resting stage, preparing for replication. S phase- chromosomes replicate
Are humans diploid or haploid?
Somatic cells diploid, sex cells haploid
How many chromosomes do humans have?
23 haploid, 46 diploid
How are meiosis and mitosis similar? Different?
Mitosis goes from diploid to diploid, meiosis goes from diploid to haploid
What are homologous chromosomes?
Alternate versions of a chromosome (one from each parent), not identical but have same
genes.
What are sister chromosomes?
Identical copies of a single chromosome, joined at the centromere
Meiosis produces how many haploid cells? Why is this important in sexual reproduction?
4 haploid cells. Important since half genetic information comes from each parent to
produce an offspring with the correct number of chromosomes (23+23=46)
What does DNA stand for?
Deoxyribonucleic acid
What are the 4 DNA bases? What two groups do they fall under?
Purines: adenine (A), guanine (G). Pyrimidines: thymine (T), cytosine (C)
Biology
Unit 2 - Genetics
Williams
Name _________________________________________________ Date: ________________________ Hr: _____________
What are the two pairings of the DNA bases?
Adenine & Thymine (A-T), Cytosine & Guanine (C-G)
How many hydrogen bonds connect each of the pairs? Which pair has a stronger bond?
A-T: 2 H bonds. C-G: 3 H bonds. C-G stronger bond.
What are the rules of DNA base composition?
Equal number of purines & pyrimidines. Equal number of A & T. Equal number of C & G
Describe the steps of DNA replication, including the 3 major enzymes.
Helicase unzips DNA, DNA polymerase reads DNA and pairs the bases with free nucleotides
from 3’ end towards the 5’ end. Okazaki fragments are formed on lagging strand, and ligase
joins the fragments.
At each replication fork, there are two growing DNA strands. What are the two strands, and
how is the replication process different at each strand?
Leading strand & lagging strand. Both read DNA from 3’-5’ but lagging DNA is replicated in
chunks (Okazaki fragments) and then joined together by ligase.
What is the central dogma of molecular biology?
DNA is transcribed to RNA and translated to an amino acid chain (protein)
What does RNA stand for?
Ribonucleic acid
What are the 3 main types of RNA?
Messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA)
What are the four bases of RNA?
Adenine (A), Guanine (G), Cytosine (C), & Uracil (U)
Biology
Unit 2 - Genetics
Williams
Name _________________________________________________ Date: ________________________ Hr: _____________
What are the two types of bases, and which ones belong to each group?
Purine: adenine & guanine, Pyrimidines: cytosine & uracil
What are the differences between RNA and DNA?
RNA has ribose instead of deoxyribose sugar base, RNA contains Uracil instead of Thymine,
and RNA is single stranded (unlike DNA double strands)
What is the basic process of transcription?
Initiation, elongation, termination
What does the promoter control?
Where the initiation site is
How do you determine which is the template & non-template strand?
The 3’ end is on the promoter side
How is RNA created using DNA?
RNA polymerase reads the DNA and creates an RNA strand based on the corresponding
nucleotide pairings.
How is the transcription process different in prokaryotes and eukaryotes?
In eukaryotes, the RNA has to leave the nucleus so it adds a 5’ cap, a poly A tail, and splicing
occurs to remove introns and splice together exons
What are the functions of the 5’ cap?
Protection, transportation and translation
What does splicing do?
Removes introns and joins exons
Biology
Unit 2 - Genetics
Williams
Name _________________________________________________ Date: ________________________ Hr: _____________
What are proteins made of?
Chain of amino acids
What are the ‘words’ that code for amino acids?
Codons
Does a codon code for more than one amino acid?
No
Can an amino acid have more than one codon that codes for it?
Yes
When does coding begin on the mRNA? (hint - when does the open reading frame begin?)
At the start codon: AUG which codes for methionine (met)
When does coding end? (hint - when does the open reading frame end?)
At a stop codon: UAA, UAG, or UGA (which do not code for any amino acids)
Where does protein synthesis take place in the cell? (what organelle?)
Ribosomes
What are the 3 translation sites on the ribosome?
E site, P site, & A site
What are the 3 steps of translation?
Initiation, Elongation, & Termination
Describe the process of translation.
mRNA
Biology
Unit 2 - Genetics
Williams
Name _________________________________________________ Date: ________________________ Hr: _____________