Unit 2

• In sexually reproducing species, offspring inherit one chromosome from each parent. Every copy of a chromosome carries the same genes.
• DNA is composed of two strands of nucleotides. Each nucleotide has sugar (deoxyribose), a negatively charged phosphate group, and a nitrogenous base.
• DNA replication is the process of copying DNA, and occurs whenever cells reproduce
• Semiconservative replication occurs because each strand of DNA serves as a template for a new, complementary strand.
• What happens after the double helix unwinds in DNA replication?

  Hydrogen bonds between bases break
• DNA polymerase is an enzyme that constructs DNA by adding complementary nucleotides to a new strand.
• Polymerase chain reaction is a chemical reaction that amplifies the amount of DNA in a sample.
• What is added to a DNA sample for PCR?

  nucleotides, DNA polymerase, primers inside a solution
• A primer is a sequence of nucleotides that tells DNA polymerase where to start
• The Human Genome Project aims to map all the three billion nucleotides in the 23 chromosomes of humans.
• Short tandem repeats are blocks of repeated DNA sequences
• DNA has coding and noncoding regions
• To create a DNA profile…

  1. Cells are collected and DNA is extracted
  2. PCR is used to amplify at least 15 STR regions
  3. Gel electrophoresis is used to separate STRs based on length
  4. A unique pattern known as a DNA profile is made, with bands representing STRs
• The National DNA Index System (NDIS) is a database of DNA profiles for convicted criminals. Each profile is unique.
• DNA is used to store and pass down biological information for ALL life forms
• A chromosome is a single, large DNA molecule wrapped around histone proteins. It’s located in the nuclei of eukaryotic cells.
• The helicase is an enzyme that unwinds and unzips the DNA’s double helix during DNA replication
• The genome is a complete set of genetic instructions encoded in the DNA of an organism
• A protein is a macromolecule made up of repeating subunits (amino acids), which determine the shape and functions of the protein.
• Beta sheets are flat, interlocking protein structures rich in hydrophobic amino acids that pack closely together, away from water.
• A gene is a sequence of DNA that contains the information to make at least one protein.
• Gene expression is the process of using DNA instructions to make proteins
• The regulatory sequence is the part of the gene that determines the timing, amount, and location of protein production
• The coding sequence is the part of the gene that specifies the amino acid sequence of a protein.
• Transcription is the first stage of gene expression, where cells produce molecules of messenger RNA from the instructions encoded within genes in DNA
• What nitrogenous bases does RNA use?

  A, U, G, C
• During transcription…

  1. In the nucleus of the cell, RNA binds to the DNA at the regulatory sequence
  2. RNA polymerase separates the two DNA strands and begins moving along one of them. It synthesizes an mRNA strand by adding complementary nucleotide bases
  3. Once finished, RNA polymerase leaves the DNA strand, which forms the double helix again.
  4. The mRNA leaves the nucleus and goes to the cytoplasm
• Messenger RNA is the RNA copy of an original DNA sequence made during transcription
• Translation is the second stage of gene expression, where mRNA sequences are used to assemble the amino acids to make a protein
• During translation…

  1. The ribosome hops onto the mRNA in the cytoplasm. The mRNA tells the organelle which amino acids should be added to the protein chain.
  2. The tRNA delivers the amino acid
  3. The tRNA’s anticodon and mRNA’s codon match to bring the correct amino acid
• The ribosome is the cellular machinery that assembles proteins during translation
• The genetic code is a set of rules that list out which mRNA codons correspond to which amino acids
• A transgenic organism is one that carries one or more genes from a different species.
• A recombinant gene is a genetically engineered gene that contains portions of genes not naturally found together
• Genetic engineering is the altering/manipulation of DNA of organisms by modern lab techniques
• A vector is a DNA molecule used to deliver a recombinant gene to a host cell
• A genetically modified organism is one whose genome has been altered via genetic engineering
• Gene therapy is a treatment that aims to cure, treat, or prevent human disease by replacing defective genes with functional ones
• Amino acids contain an amine group, a carboxyl group, and a side chain.
• A mutation is any change in the sequence of DNA