Molecular Genetics Chromosome Structure  DNA coils around histones to form nucleosomes, which coil to form chromatin fibers.  The chromatin fibers supercoil to form chromosomes that are visible in the metaphase stage of mitosis.

Molecular Genetics DNA Structure  The shape of DNA is a twisted ladder which is called a double helix  DNA is made up of nucleotides  Nucleotides consist of a five-carbon sugar (deoxyribose), a phosphate group, and a nitrogen base  The bases pair together to connect the strands

The Structure of Nucleotides

Molecular Genetics DNA Structure cont’d -Two outside strands consist of alternating deoxyribose and phosphate -Cytosine and guanine bases pair to each other by three hydrogen bonds - Thymine and adenine bases pair to each other by two hydrogen bonds

Molecular Genetics Rails of the ladder are represented by the alternating deoxyribose and phosphate. The pairs of bases (cytosine–guanine or thymine–adenine) form the steps.

DNA The information in DNA is contained in the order of the bases. The base pairing allows DNA to be copied. The bases are held together by weak Hydrogen bonds

DNA Replication Explains how DNA makes a copy of itself

Molecular Genetics DNA Replication  DNA helicase, an enzyme( a type of protein), unwinds DNA by breaking the hydrogen bonds hold DNA together  DNA polymerases adds nucleotides to match up with the exposed ends of the DNA to create two copies from the parent copy

Activity Use string and glue to visualize and explain the process of transcription You need to have at least three step. Use words and string to describe each step.

RNA

Molecular Genetics  RNA  Single stranded  Contains the sugar ribose and the base uracil

3 types of RNA Messenger RNA (mRNA)- carries instructions for making proteins during translation. mRNA transcribes the genetic code from DNA into a form that can be read and used to make proteinsthe genetic code Transfer RNA- (tRNA)- translates the mRNA sequence into specific amino acids because they have amino acids attached to them Ribosomal RNA(rRNA)- rRNA directs the translation of mRNA into proteins.the translation of mRNA

DNA vs RNA

DNARNA NameDeoxyribonucleic acidRibonucleic acid StructureDouble strandedSingle stranded FunctionBlue printCarries blue print’s information Base pairingAT, GCAU, GC

Proteins Proteins are the building blocks of life Proteins are involved in just about all cell functions Proteins are used for hormones, antibodies, structural support, enzymes, storage, transport

Protein Synthesis or Gene Expression ( how DNA codes for traits) Gene expression produces proteins by transcription and translation It occurs in all cells All of the steps of gene expression include RNA

Transcription ( DNA to RNA) This is the first stage of gene expression Transcribing( writing) DNA information onto messenger RNA.

Transcription DNA unwinds and uses an enzyme ( RNA polymerase) to make mRNA The Code on DNA is transferred to mRNA (messenger RNA) mRNA takes the code to the ribosome in the cytoplasm to be used in protein synthesis

Translation This is the second stage of gene expression Translation is the process of translating the information on messenger RNA (mRNA) molecule amino acids during protein synthesis.

Translation( RNA to Proteins) The mRNA is attaches to a ribosome which has rRNA(ribosomal) and tRNA (transfer) The tRNA sends a signal to start the process tRNA (transfer RNA) reads the base sequence on mRNA and adds complimentary amino acids ( the building blocks of proteins). The tRNA reads the codes on the mRNA in three’s which is called a condon if this is not read properly it can create mutations the tRNA connects to the matching bases on the mRNA and leave an amino acid to create a big chain of amino acids is formed and held together by peptide bonds (protein bond)