Unit 6 Complete Student Notes_2024

Heritable information

Genetic information that is passed down from one generation to the next.

Phenotypic differences

Differences in observable traits or characteristics between organisms.

Genetic variation

Differences in the genetic makeup of individuals within a population.

DNA

Deoxyribonucleic acid, the molecule that carries genetic information in all living organisms.

RNA

Ribonucleic acid, a molecule involved in various cellular processes, including gene expression.

Prokaryotic cell

A type of cell that lacks a nucleus and other membrane-bound organelles.

Eukaryotic cell

A type of cell that has a nucleus and other membrane-bound organelles.

Chromosome

A structure made of DNA and proteins that carries genetic information.

Plasmid

A small, circular DNA molecule that can be found in some prokaryotes and some eukaryotes.

Gregor Mendel

An Austrian monk who discovered the basic laws of inheritance through his work with pea plants.

Proteins

Large molecules made up of amino acids that perform various functions in cells.

Transformation experiment

An experiment conducted by Frederick Griffith to study the exchange of genetic information between bacteria.

Oswald Avery

A scientist who identified DNA as the "instructional agent" responsible for the transformation of bacteria.

Alfred Hershey and Martha Chase

Scientists who used bacteriophages to definitively show that DNA, not proteins, serves as the genetic material.

Bacteriophage

A virus that infects bacteria.

Capsid

The protein coat of a virus.

Radioactive labeling

The process of attaching a radioactive isotope to a molecule for tracking purposes.

Sulfur 35

A radioactive isotope of sulfur used by Hershey and Chase to label the protein coat of bacteriophages.

Phosphorus 32

A radioactive isotope of phosphorus used by Hershey and Chase to label the DNA of bacteriophages.

Transduction

The process by which a virus transfers genetic material from one bacterium to another.

Bacteriophages

Viruses that infect bacterial cells and use them as hosts to make more viruses.

Horizontal gene transfer

The movement of genetic material between organisms other than by the transmission of DNA from parent to offspring.

Chargaff's Rules

The discovery by Erwin Chargaff that the amounts of Adenine (A) are equal to the amount of Thymine (T) and the amount of Cytosine (C) is equal to the amount of Guanine (G) in DNA.

Double helix

The structure of the DNA molecule, consisting of two strands of nucleotides twisted together.

Nucleotides

The monomers that make up DNA, consisting of a sugar molecule, a nitrogenous base, and a phosphate group.

Complementary base pairing

The specific pairing of Adenine (A) with Thymine (T) and Cytosine (C) with Guanine (G) in DNA.

Purines

Nitrogenous bases with a double ring structure, including Guanine and Adenine.

Pyrimidines

Nitrogenous bases with a single ring structure, including Cytosine, Thymine, and Uracil.

Antiparallel

The orientation of the two strands of DNA, running parallel to each other but in opposite directions.

DNA Replication

The process by which a cell makes a complete copy of its DNA.

Origins of Replication

Specific nucleotide sequences in DNA that act as starting points for DNA replication.

How Many Origins of Replication Are in Prokaryotes?

One Origin of Replication

How many origins of Replication do Eukaryotes have?

Multiple on each straight chromosome.

Helicase

An enzyme that unwinds or unzips the two strands of DNA during replication.

DNA replication

The process by which a cell makes an identical copy of its DNA.

Single-stranded binding proteins

Proteins that attach to unzipped DNA strands to keep them separated and stable during replication.

Replication bubbles/forks

Regions where DNA replication occurs, with multiple bubbles/forks forming on each DNA strand.

Topoisomerases

Enzymes that untangle and relax the supercoiling of the DNA double helix ahead of the replication fork.

Primase

An enzyme that synthesizes short RNA sequences called primers, which serve as starting points for DNA synthesis.

DNA polymerase III

Enzymes that attach to the RNA primers and create the new strand of DNA.

DNA Polymerase I

Replaces the RNA primers with DNA to form a more complete replicated strand.

Elongation

The process of adding new nucleotides to the new DNA strands using DNA polymerase. This can also happen in Translation when protein synthesis occurs. Amino acids are linked together to form a protein

Okazaki fragments

Short fragments of DNA synthesized on the lagging strand during DNA replication.

Ligase

An enzyme that joins or "stitches" the Okazaki fragments together during DNA replication. After DNA polymerase I replaces RNA primers.

Semiconservative process

The process of DNA replication where each of the two original DNA strands acts as a template for the building of new complementary strands, resulting in two identical copies of the original molecule with one strand of the original in each new strand.

Proofreading

The process by which DNA polymerases check their work and remove and replace incorrectly paired nucleotides during DNA synthesis.

Mismatch repair

The process of removing and replacing mis-paired bases in newly synthesized DNA that were not fixed during proofreading.

Telomeres

Repeated DNA sequences at the ends of chromosomes that protect the genes located there from deterioration.

Leading strand

The DNA strand that is synthesized continuously during DNA replication.

Lagging strand

The DNA strand that is synthesized discontinuously in small pieces called Okazaki fragments during DNA replication.

Telomere shortening

The gradual shortening of telomeres with each round of DNA replication, which limits the number of cell divisions and is associated with aging and lifespan limitations.

Telomerase

An enzyme that lengthens telomeres during fetal development and can become active again in some mutated cells, leading to cancer.

Central Dogma of Genetics

Describes the flow of genetic information from DNA to mRNA to protein, including the processes of transcription and translation.

Replication

The process of creating an identical copy of the entire genome during the S phase of Interphase.

Retroviruses

Viruses that transcribe RNA into DNA using reverse transcriptase, integrating the DNA into the host cell's genome.

Prions

Proteins that can replicate themselves by making conformational changes in other proteins, violating the central dogma.

Protein Synthesis

The process of using DNA converted into mRNA to code for proteins, which make up a large part of the body's structure and functions.

One gene-one enzyme hypothesis

The idea that a single gene has the genetic information for making one enzyme, later changed to the one gene-one polypeptide (protein) hypothesis.

Transcription

The process of using DNA as a template to make mRNA, which carries the protein-building directions to the ribosomes.

Initiation

The first phase of transcription, where transcription factors attach to the promoter region and RNA Polymerase attaches to the promoter.

Elongation

The phase of transcription where RNA Polymerase uses the template strand of DNA to build an RNA molecule.

Template strand

The DNA strand used by RNA Polymerase as a template to build the RNA molecule during transcription.

Termination

The process in which the RNA Polymerase reaches the end of the gene and stops transcription, signaled by a stop or terminator sequence in the DNA.

RNA Processing or RNA Modification

The series of enzyme-regulated modifications that the newly formed pre-mRNA molecule undergoes in eukaryotic cells before it can be turned into mRNA and used for translation.

Front end or 5' modification

The addition of a protective GTP cap to the 5' end of the RNA molecule during RNA processing(only eukaryotes), helps the mRNA molecule attach to the ribosomes.

Back end or 3' modification

The addition of 50-250 adenine nucleotides, known as a Poly A Tail, to the 3' end of the RNA molecule during RNA processing (only eukaryotes), prevents enzymatic breakdown and aids in exporting the RNA molecule out of the nucleus.

Splicing or Middle Modification

The process of removing intron sequences and splicing together exon sequences in the RNA molecule during RNA processing, carried out by spliceosomes in multicellular eukaryotes.

Introns

Non-coding regions in the RNA sequence that must be removed or excised during splicing to make the RNA functional.

miRNAs

MicroRNA molecules that are derived from introns and bind with mRNA to prevent translation, playing a critical role in gene expression regulation.

mRNA (Messenger RNA)

Carries information from DNA to the ribosomes and encodes the amino acid sequences of polypeptides (Codons)

tRNA (Transfer RNA)

Binds to specific amino acids and delivers them to the ribosomes during translation, generating the primary sequences of polypeptides (Anti-Codons)

rRNA (Ribosomal RNA)

Serves as the functional building blocks of ribosomes, which translate the mRNA.

snRNA (Small nuclear RNA)

Forms complexes/spliceosomes used in RNA processing in eukaryotes.

Translation

The process in which ribosomes read the information encoded in mRNA (sets of three nucleotides aka. codons), and use it to generate a polypeptide chain of amino acids.

Codon

A set of three mRNA nucleotides that codes for a specific amino acid during translation.

Start Codon

The codon AUG, which codes for the amino acid methionine and signals the beginning of protein synthesis.

Stop Codons

The codons UAA, UAG, and UGA, which do not code for amino acids but signal the end of protein synthesis.

Genetic Code

The universal code that determines the relationship between codons and the amino acids they code for.

tRNA (Transfer RNA)

Molecules that bind to specific amino acids and transport them to the ribosome during translation, based on the codons they can bind to (anit-codons).

Ribosomes

Structures made of rRNA and proteins that organize translation and catalyze the reaction that joins amino acids to make a polypeptide chain.

Translation

The process of protein synthesis that occurs inside ribosomes, where the sequence of nucleotides on mRNA is read and translated into a polypeptide chain.

Initiation

The first stage of translation, where the initiator tRNA carrying methionine attaches to the small ribosomal subunit and binds to the 5' end of the mRNA, followed by the attachment of the large ribosomal subunit.

Termination

The final stage of translation, where translation is stopped when a stop codon on the mRNA enters the A site of the ribosome, and the newly synthesized polypeptide chain is released from the ribosome.

Anticodon

A sequence of three nucleotides on tRNA that is complementary to the codon on mRNA.

Wobble Effect (Silent Mutation)

An effect caused by the redundancy in the genetic code, where the third nucleotide in a codon can change without affecting the amino acid inserted during translation.

Post-Translation Modification

The process of folding a polypeptide chain into its proper three-dimensional shape and adding functional groups, such as carbohydrates or lipids, to the protein.

Chaperonins

Proteins that assist in the folding of polypeptide chains and provide a favorable environment for the folding process.

Phosphorylation

The addition of a phosphate group to a protein, usually from ATP or GTP, which activates or deactivates enzymes.

Ubiquitination

The process of adding ubiquitin, a small regulatory protein, to a protein, often marking it for degradation in the cell's proteasomes.

Mutations

Changes in the nucleotide sequence of DNA or mRNA that code for a protein, which are the primary source of genetic variation.

Mutagens

Physical or chemical factors that can change the nucleotide sequence of DNA, such as ultraviolet radiation, gamma rays, X-rays, cigarette smoke, certain viruses, insecticides, pesticides, and reactive chemicals.

Point Mutations

Mutations in which a single nucleotide is changed to another, incorrect nucleotide, resulting in three major types:silent point mutations, missense point mutations, and nonsense point mutations.

Silent Point Mutations

Mutations in which no change in the amino acid sequence occurs because the new codon still codes for the same amino acid as the original codon.

Missense Point Mutations

Mutations in which the amino acid coded for by the original DNA sequence is replaced by a different amino acid, potentially causing dramatic effects if the chemical properties of the original and new amino acid are very different.

Sickle Cell Anemia

A genetic disorder caused by a point mutation in the gene for hemoglobin, resulting in the replacement of glutamic acid with valine and leading to misshapen red blood cells and various symptoms.

Nonsense Point Mutations

Mutations in which a single nucleotide substitution causes a codon that normally codes for an amino acid to become a stop codon, resulting in premature termination of translation and no synthesis of functional protein.

Frameshift Mutations

Mutations in which nucleotides are either deleted or inserted (in numbers that are not a multiple of 3), causing changes in the shape of the affected protein and usually more severe effects than point mutations.

Tay Sachs Disease

A genetic disorder caused by a frameshift mutation in the HEXA gene, resulting in the accumulation of gangliosides in the brain and leading to various symptoms including deafness, blindness, muscle weakness, seizures, and delayed development.

Gametic Mutations

Mutations that occur in germ cells or gametes can be passed on to offspring and contribute to evolution, while mutations in somatic cells are not passed on and do not contribute to evolution.

Natural Selection

The process by which genetic changes that enhance survival and reproduction are selected for by environmental conditions.