Biology Quiz

Mutation

• A change in the sequence of DNA

• Caused by a mistake in any of the following:

  • Copying DNA (Replication)

  • Cell division

  • Writing from DNA (Transcription)

• Mutation is usually bad, but provides new genetic variation for evolution to work with

Why does Mutation happen?

• An outside factor that causes mutations is called a mutagen

  • Can interfere with the cellular machinery working with the DNA or interfere w/ DNA directly

• Examples:

  • Radiation (x-rays, UV light)

  • Certain chemicals (smoke, pollutants)

  • Environmental stress

• Sometimes just an unprompted mistake

How do you read DNA?

• DNA is read in group of three called codons

• A mutation can cause DNA to read as a different codon or many different codons

• Gene mutations: affects one gene

• Chromosomal mutations: affects a large portion of a chromosome (where many genes are)

Gene mutations

affects one gene

Chromosomal Mutations

affects a large portion of a chromosome (where many genes are)

What is point mutation?

• A Point mutation occurs when a base is accidentally exchanged for another base

• Example:

  • Original DNA reads: ATACG

  • After point mutation: ATGCG

What is Frameshift?

• A Frameshift mutation is caused by an addition or deletion of a base

• Example: (Addition)

  • Original DNA reads: ATACG

  • After mutation: ATATCG

• Example: (Deletion)

  • Original DNA reads: ATACG

  • After mutation: ATCG

What is a chromosomal mutation

• Large sections of DNA are moved, flipped around, lost, or added

• Can cause drastic changes because it can affect many genes

Body Cells

• Mutations passed on to new cells by mitosis

• Cannot be passed on to offspring

• Can inhibit formal function or change characteristics of the cell

• Is thought to be part of the aging process

Sex Cell Mutations

• Mutations in the “germ line”

• Can be passed on to offspring

• Responsible for all new traits in a gene pool

• Are the driving force behind evolution

Why are sex cell mutations (germ cells) passed down and why are body cell mutations not?

• Sex cell mutations occur in reproductive cells which are part of the genetic material transmitted to the offspring

• Body cell mutations do not contribute to the genetic makeup of the offspring

Parts of transcription

• DNA to mRNA

Parts of translation

• mRNA to tRNA

Two differences between DNA and RNA

• Different sugars

• Single stranding vs double stranding

• Different bases (U instead of T for RNA)

differences between tRNA and DNA

• Sugar is ribose, not deoxyribose

• RNA is single stranded that carries amino acids to the ribosomes during translation and DNA is double stranded that stores genetic information

• Uracil, not thymine

DNA

• Deoxyribonucleic Acid

• Molecule that contains all of the information needed to build/operate an organism

Nucleotide

1 unit base, sugar, phosphate

Semiconservative Replication

• A process where a DNA molecule is duplicated, resulting in two new DNA molecules, each containing one original strand and one newly synthesized strand

The Four Bases

• Adenine (A)

• Cytosine (C)

• Thymine (T)

• Guanine (G)

Transcription

• An enzyme (RNA Polymerase) unzips part of the DNA where a gene is located

• mRNA nucleotides match up w/ unzipped DNA

  • like when DNA replicates

• Resulting mRNA edited, then leaves the nucleus

Translation

• Occurs outside nucleus

• tRNA anticodons each are bonded with a specific amino acid

• mRNA codons match up w/ tRNA anticodons

Protein Synthesis

• tRNA hands off amino acids to ribosome

• Ribosome combines amino acids in correct order to make a chain called a polypeptide

• Polypeptide folds up and becomes a protein

  • Shape is important