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Chapter 9 Study Guide

Terms in this set (28)

Genotype
The types of genes that an organism has
Phenotype
The way those genes are expressed to give an organism specific traits
Genes
Segment of DNA that has the code for one protein or one RNA
Chromosomes
A neatly packaged DNA molecule (in bacteria)
Genome
Sum total of genetic material of an organism
How many genes do the smallest viruses have?
4-5 genes
How many genes does a human cell have?
20,000-25,000 genes
How are bacterial and eukaryotic chromosomes different?
- Bacteria only have some chromosomes
- Eukaryotes have two or more chromosomes
Describe the structure of the DNA molecule, including the parts making up each nucleotide, the direction of the strands, and how the strands are connected
- Nucleotide = nitrogenous base (A, T, C, G) + deoxyribose sugar + phosphate

- Antiparallel

- The strands are connected by hydrogen bonds
Replication Fork
The mechanism by which a strand of DNA is synthesized
Binary Fission
Cell division in bacteria
Know what is synthesized in each of the three processes: Replication , Transcription, and Translation
Replication: two new strands of DNA

Transcription: RNA

Translation: protein synthesis
When DNA replication occurs, where do the two parent strands end up?
At a replication fork where they are used for the synthesis of two new strands acting as the template
What are the 3 steps of DNA replication?
1) Uncoiling of double helix (topoisomerase)

2) Unzipping of two strands (helicase)

3) Synthesis of two new strands using the two parent strands as templates (DNA polymerases and others)
What is a codon?
The 3-nucleotide sequences that each (messenger RNA) code for an amino acid
What are the four different RNA products of transcription, and what do they do?
Transfer RNA - used in translation

Messenger RNA - the template for translation

Ribosomal RNA - builds ribosomes

Various types of regulatory RNAs (used to be called "junk")
What is found at the end of a tRNA molecule?
Stop codon
What are the key differences between DNA and RNA structure?
DNA - deoxyribose - T

RNA - ribose - U

In RNA only 1 strand of RNA is transcribed
What kind of molecules regulate which genes are transcribed and translated?

Why is this regulation important? (why doesn't the cell want to transcribe the whole genome all the time?)
Regulatory RNAs determine which genes need to be transcribed

The cell only transcribes what it needs
Mutation
any change in the nucleotide sequence of DNA
Spontaneous Mutation
Unfixed misspellings
Induced Mutation
Damaged DNA
Mutagen
Agents that can disrupt DNA
Sexual Reproduction
Swap DNA with other bacteria
What are two likely results of mutation?
- Nonfunctional proteins

- Faulty regulatory DNA
What is one example of a positive outcome of a mutation?
- Lots of opportunities for shifting DNA through generations

- Challenging environments that weed out those with "weak" traits
What are some phenomena that lead to changes in DNA over many generations?
- Sexual reproduction

- Viruses messing with DNA

- Mutations
How do bacteria obtain antibiotic resistance?
- Genetically mutate

- Acquiring from another bacterium
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