Nucleic Acids and Protein Synthesis I love the color selection from MS PowerPoint

DNA: Structure Double Helix: Twisted ladder shape of DNA

DNA: Structure Monomer: _____________ 5 Carbon Sugar (_________________) Phosphate Nitrogenous Base (2 kinds)

Types of Nitrogenous Bases Purines: Adenine (A) Guanine (G) Pyrimidines Thymine (T) Cytosine (C) Uracil (U) – Not in DNA

Nucleotide Structure

DNA Structure Double stranded molecule (Ladder) Rungs: Nitrogenous bases Uprights: Alternating Sugar and Phosphates

DNA Structure Antiparallel: The 2 strands run in opposite directions

Antiparallel

DNA Structure The bases connect the two strands of DNA Each base ONLY bonds to a corresponding base A – T G – C NO EXCEPTIONS = Mutations Practice: AAGTACTAGATTACCG

Double Helix Why does the DNA ladder twist into a double helix? ANSWER: Hydrophobic vs Hydrophilic interactions

A DNA Review What are the three components of a nucleotide? DNA ladder: rungs and uprights Antiparallel Hydrogen bonding between bases Double helix and Hydrophobicity

Famous Scientists Chargaff’s Rules (%A = %T, %G = %C) Rosalind Franklin (X-Ray Crystallography) DNA = 2 strands that coil around one another

Famous Scientists Take 2 Watson and Crick (1953) 3D molecule of DNA (Double Helix) Hydrogen bonds between purines and pyrimidines

DNA and Chromosomes Prokaryotic Cells (No True nucleus) DNA arranged in a large circle OR DNA found in small circles (plasmids)

Eukaryotic Cells (True Nucleus) DNA is on several linear chromosomes in the nucleus Each species has its own unique number of chromosomes Humans – 46 Fruit fly – 8 Giant Sequoia Tree – 22

DNA is huge . . . How can it fit in the nucleus? DNA winds around protein complex (Histones)

How it fits continued… DNA and Histone complex coil to form a Nucleosome Nucleosomes coil tighter (Supercoil) to form a chromomome

Histones and Evolution Histones are very conserved throughout among different species Conserved – similar structure and amino acid sequence due to evolution WHY???

DNA Replication When does it occur? Why does it occur? How does it occur (5 steps)? Uncoil Unzip Add parts Recoil Proof-read

DNA Replication Take 2 The process is controlled by many enzymes Steps in detail: Uncoil Unzip DNA helicase unzips the 2 DNA molecules by breaking the Hydrogen bonds between the bases Typically begins at a site rich in A’s and T’s. WHY?

DNA Bases

Result: Replication Fork

DNA Replication Add parts Each strand serves as a template for the construction of a seconds strand of DNA Problem: The 2 strands are anti-parallel Solution: One strand copied continually – Leading strand One strand copied in segments – Lagging strand

DNA Replication Leading strand = 3’  5’ Lagging strand = 3’  5’ but leaves gaps Gaps = Okasaki Fragments

DNA Replication 3. Add Parts DNA Polymerase begins adding corresponding nucleotides to the template strands EX) ATTATACG TAATATGC When finished, DNA Polymerase comes back and fills in the gaps (Okasaki fragments)

DNA Replication 4. DNA Recoiled 5. DNA is proof-read DNA Polymerase proof-reads the 2 strands of DNA for any mistakes Result: 2 strands of DNA  Semi-conservative: Definition?

Sex Determination and Sex Linkage Sex is determined by the 23rd chromosomes XX = XY =

Chances of Having Male vs Female Child Hypothetical Sex ratio: Birth Ratio: Population Ratio: Kutztown Ratio:

X-Linked Traits The x chromosome is bigger than the y and therefore holds more genes Examples: - Hemophilia - Red/Green Color-blindness - Baldness

Sex Linked crosses These are all recessive traits (For our purposes) Females must have two bad copies in order to be infected XX XXC XCXC Males only need one bad copy XY XCY

Morale of this story Who is responsible for a son being bald? Cross One: Cross a bald man with a homozygous normal woman Cross Two: Cross a normal man with a woman carrying the bald gene.

RNA and Protein Synthesis RNA (Ribonucleic Acid Type of Nucleic Acid (3 parts)

RNA VS DNA RNA is single stranded RNA’s sugar is Ribose, not Deoxyribose RNA uses Uracil (U) as a base rather than Thymine (T) Uracil connects to Adenine (A)

Types of RNA Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA)

What is the job of RNA Ribosome