Chapter 16: Intro to DNA structure

Genetics

Study of genes in DNA, and how the information in these genes are interpreted in proteins and transmitted through generations

Deoxyribonucleic acid (DNA)

start of genes, instructions to make ribonucleic acid (RNA

Genes

smaller segments in DNA and is a cod typically for RNA & proteins

Alleles

different versions of genes (ex. eye color)

Genome

all the DNA that a cell has (chromosomes & plasmids)

Chromosomes

DNA + protein

Plasmid

small circular DNA molecules found in bacteria and other organisms

Genotype

the genes you have & alleles

Phenotype

physical appearance (ex.visual eye color — brown)

Gene Expression/Central Dogma

Take the information from DNA → Use DNA to make RNA → Take RNA information to make Protein (or a polypeptide chain which folds into a protein)

Nucleic Acid

A macromolecule responsible for storing, transmitting, and expressing genetic information in all living organisms

Nucleic Acid Monomers

Nucleotide

Nucleic Acid Polymers

Nucleotides

DNA structure

Double-stranded, folded into a double felix

RNA structure

single-stranded, can take on secondary structure

Nucleotide structure

phosphate group, sugar (deoxyribose or ribose), nitrogenous base (purines & pyrimidines)

Deoxyribose structure

hydrogen group

Ribose structure

hydroxyl group

Purines

Adenine (A), Guanine (G) — double ring structure

Pyrimidines

Cytosine (C), Thymine (T, only DNA), Uracil (U, only in RNA) — single ring structure

Phosphodiester bonds

one end of individual nucleotides (DNA), connected to each other to another end (RNA)

Sugar-phosphate backbone

creation of phosphodiester bonds (sugar & phosphate) which get repeated down a DNA strant

Directionality of a DNA strand

based on sugar orientation, 5’ end to the 3’ end

DNA double helix

Two strands of DNA winded around each other

Single Strand DNA

contains nitrogenous bases

Two strand DNA

nitrogenous bases stick outwards towards each other, forming hydrogen bonds — complementary

Base pairs

nitrogenous bases that bond together specifically (AT/GC rule)

Complementary

5’ CGGATC 3’ → 3’ GGCTAG 5’ (antiparallel)

Supercoiled

DNA is compacted to fit inside a cell, and proteins help with compaction

Bacterial DNA

one circular chromosome attached to the plasma membrane within the nucleoid, it may or may not have a plasmid

Eukaryotic DNA

multiple linear chromosomes (DNA + histone proteins), located in the nucleus, mitochondria, and chloroplasts