Lecture 2: Review of Basic Biology Flashcards
Cell Theory
- Cells are an organism’s basic structure and function
- All organisms are made of cells
- All cells come from pre-existing cells
Three Domain Classification
Bacteria (P), Archaea (P), and Eukarya (E)
Genome
- Complete set of DNA in an organism’s nucleus and mitochondria (and chloroplast)
- nucleus contains most of the cell’s DNA while additional genes are located in the mitochondria and chloroplasts of eukaryotic cells
Genomics
Large-scale study of sets of genomes between species
Basic Feature of Cells
- Enclosed by plasma membrane which regulates the passage of materials between the cell and surroundings
- Cytosol
- DNA as genetic information
- RIbosomes that make protein
Human Genome Project
Sequencing of the entire 3 billion subunits of the human genome. Identified all human genes and made them accessible for further studies.
Founded by Craig Venter and Francis Collins
Chromatin
A complex of DNA and proteins, when cells are not dividing, chromatin exists in dispersed form. In eukaryotes, during cell division chromatin condenses to form discrete chromosomes.
Gene
- Unit of inheritance that is a sequence of nucleotides on DNA that provide cells with the information needed to produce a specific protein
- Responsible for organisms’ traits (inherited physical appearance), some traits are controlled by a single gene while some are by multiple
- 23 Chromosomes from mom and 23 from dad, Haploid (n)-23 and diploid (2n)-46, each chromosome contains hundreds- thousands of genes
Oswald Avery
Discovered isolation of pure DNA
James Watson and Francis Crick
Proposed double-helical model for the structure of DNA
- model demonstrated how the molecule can carry information to serve as a template for its duplication and for the synthesis of protein
Pyrimidine
Bases have a 6-member ring with 4 carbons and 2 nitrogen
example: Cytosine, Uralic (R), THymine (D)
Purine
Bases that have a 9 member double ring system with 4 nitrogen and five carbon
example: Adenine and Guanine
Nucleotides
Building blocks (monomers) of DNA
-3 main chemical groups: phosphate, pentose sugar, and a nitrogenous base
- The four nucleotides differ by their nitrogenous bases
DNA
- consists of 2 anti-parallel strands that are in a double helix
- polarity between the strands with a free phosphate group on 5’ and a free hydroxyl group on 3’ end
- paired strands stabilized by H-Bonds that are weak and form when + charge attracted to negative charge (AT and GC)
Origins of Replication
Regions where two DNA strands are separated, opening up a replication bubble
Replication fork
Where new DNA strands elongate
Helicases
Enzymes that untwist the double helix at the replication fork
Single-strand binding (SSB) proteins
Bind and stabilize the unwound DNA until it can be used as a template for DNA replication
Gyrase
Corrects over winding ahead of replication forks by breaking, swiveling, and rejoining DNA strands
DNA Polymerase III
Catalyzes the addition of nucleotides to generate new polynucleotide strands of DNA
RNA Primer
Generated by an enzyme called primase
Primase
Adds RNA nucleotides one at a time at the replication fork, using parental DNA as a template to generate an RNA primer
DNA Polymerase I
Removes RNA primer and replaced with DNA nucleotides
DNA ligase
Joins sugar-phosphate backbones of all Okazaki fragments together into a continuous DNA
Telomeres
-Repetitive nucleotide sequences at the end of eukaryotic chromosomes (TTAGGG)
-they do not contain genes instead they protect genes from being eroded through multiple rounds of DNA replication
Telomerase
- Keeps telomeres from being eroded
- Telemorerase activity declines after birth and are highly active in most cancers
