Key Concepts of Nucleic Acids and Protein Synthesis

Types of nucleic acids

DNA and RNA

Information stored by nucleic acids

Genetic information for building and maintaining an organism

Single-stranded nucleic acid

RNA

Role of histones in DNA structure

Histones help package and organize DNA into chromatin

Nucleotides in DNA structure

Nucleotides are the building blocks of DNA

Components of a single nucleotide

A phosphate group, a sugar (deoxyribose), and a nitrogenous base

Sugar molecules in DNA vs. RNA

DNA has deoxyribose; RNA has ribose

Nucleotide bases in DNA vs. RNA

DNA: A, T, C, G; RNA: A, U, C, G

Structure of a polynucleotide

A polynucleotide consists of a sugar-phosphate backbone with nitrogenous bases attached

Double-helix definition

A double-helix is two strands twisted around each other

Unique structure in different DNA molecules

The sequence of the four bases is unique

Bonds holding base pairs together

Hydrogen bonds

Base pairs that always pair up

A-T and C-G

Significance of DNA replication to mitosis

Ensures each daughter cell gets identical genetic material

Semi-conservative replication

Each new DNA molecule consists of one original strand and one new strand

Enzyme that peels apart DNA strands

Helicase

Enzyme adding complementary DNA bases

DNA polymerase

Enzyme joining DNA fragments

DNA ligase

Structural difference: Number of strands

DNA: double-stranded; RNA: single-stranded

Structural difference: Type of sugar

DNA: deoxyribose; RNA: ribose

Structural difference: Type of bases

DNA: thymine (T); RNA: uracil (U)

Why DNA is called the 'molecule of heredity'

DNA carries genetic instructions for traits

Relevance of the 'Central Dogma of Life'

Yes, it describes the flow of genetic information

Importance of proteins in the human body

Proteins perform essential functions like structure, enzymes, and signaling

Relation between proteins and physical traits

Proteins determine physical traits by controlling cell functions

First step of Protein Synthesis

Transcription

Location of transcription in a cell

Nucleus

Special type of RNA produced during transcription

Messenger RNA (mRNA)

Why mRNA can leave the nucleus

mRNA is small enough to leave the nucleus

mRNA has _____ instead of thymine

uracil

Second step of Protein Synthesis

Translation

Uracil

A nucleotide found in RNA that replaces thymine.

Translation

The second step of protein synthesis that occurs in the cytoplasm at the ribosome.

Ribosomes

Cellular structures that read mRNA and assemble proteins.

mRNA codon

A three-nucleotide sequence in mRNA.

Association of mRNA codons and amino acids

Each codon codes for a specific amino acid.

Polypeptide

A chain of amino acids that forms a protein.

Gene

A segment of DNA that codes for a protein.

Types of RNA

mRNA, tRNA, rRNA.

Significance of ribosomes in translation

Ribosomes facilitate protein synthesis.

Ribosome location

Found in the cytoplasm and rough ER.

Composition of ribosomes

Made of protein and rRNA.

Function of tRNA

Transfers amino acids to ribosomes during translation.

Codon encoding

One codon encodes one amino acid.

Anticodon location

Found on tRNA.

Amino acid location

Found on tRNA.

Start and stop codons

Start codon (AUG) signals beginning; stop codons signal end.

Steps of translation

Initiation, elongation, and termination.

Ribosome subunits assembly

The ribosome subunits assemble on mRNA.

Polypeptide chain growth

New amino acids are added, forming a growing chain.

Mutation

A change in DNA sequence.

Mutations and natural selection

Beneficial mutations can drive evolution.

Mutagen

An agent that causes mutations.

Carcinogen

A substance that causes cancer.

Examples of carcinogens

UV radiation, tobacco smoke, asbestos, radiation exposure.

Point vs. frameshift mutations

Point: changes one nucleotide; Frameshift: insertion/deletion shifts reading frame.

Types of point mutations

Silent mutation (harmless), Nonsense mutation (dangerous).

Types of frameshift mutations

Insertion and deletion.

Cancer

A disease that occurs when a cell loses its ability to control its cell cycle.

Tumor

A mass of abnormal cells.

Cell cycle control system

Regulates timing of cell division.

Proto-oncogene vs. oncogene

Proto-oncogene: normal growth gene; Oncogene: mutated, leads to cancer.

Function of growth factor

Signals cells to divide.

Mutation in growth factor gene

Leads to uncontrolled cell division (cancer).

Biotechnology

Using living organisms to develop useful products.

DNA technology

Techniques for analyzing and manipulating DNA.

Genetic engineering

Modifying DNA for a purpose.

Example of genetic engineering

Producing genetically modified crops.

Function of restriction enzyme

Cuts DNA at specific sequences.