Combined Cell/Molecular Bio & Heredity

Cell Theory

All living organisms consist of one or more cells.

RNA World Hypothesis

Self-replicating RNA molecules were life's precursors.

Central Dogma of Biology

Genetic information flows from DNA to RNA to protein.

Polymerase Chain Reaction (PCR)

Amplifies DNA sample through denaturation, annealing, elongation.

Denaturation

High heat separates double-stranded DNA during PCR.

Annealing

Cooling allows primers to attach to DNA strands.

Elongation

Polymerase synthesizes new DNA strands during PCR.

Centrifugation

Separates components of a liquid sample by spinning.

DNA Sequencing

Determines the sequence of base pairs in DNA/RNA.

Blotting Techniques

Identifies specific DNA, RNA, or protein fragments.

Southern Blotting

Technique for detecting specific DNA sequences.

Northern Blotting

Technique for detecting specific RNA sequences.

Western Blotting

Technique for detecting specific protein sequences.

Gel Electrophoresis

Separates DNA by size and charge using a gel.

Microarray Assays

Monitors expression of large gene groups in genomes.

Recombinant DNA

Contains DNA segments from multiple sources.

Restriction Enzymes

Cut DNA at specific sequences to create sticky ends.

DNA Ligase

Connects DNA fragments to form recombinant DNA.

Transformation

Introducing plasmid DNA into bacteria for cloning.

Gene Libraries

Collections of DNA pieces from a genome.

Dideoxy Chain Termination

DNA synthesis requires free OH group on 3' carbon.

Confocal Laser Scanning Microscope

Uses fluorescent tagging to observe specific cell parts.

Light Microscope

Uses visible light to view thin biological samples.

Scanning Electron Microscope

Views surfaces of 3D objects with high resolution.

Genome Size

Total number of nucleotides in an organism.

Gene Number

Total number of coding sequences in an organism.

Gene Density

Ratio of gene number to genome size.

Repetitive DNA

Non-coding DNA unrelated to organism function.

Unique DNA

Coding sequences specific to an organism.

Transposable Elements

DNA sequences that can change positions within the genome.

Alternative Splicing

Single gene produces multiple protein products.

Introns

Non-coding regions within genes, absent in prokaryotes.

Exons

Coding sequences that remain in mRNA after splicing.

Epigenetics

Study of heritable changes without altering DNA sequence.

DNA Methylation

Addition of methyl groups, silencing gene expression.

Histone Acetylation

Modification that increases gene expression accessibility.

Genomic Imprinting

Expression of genes depending on parental origin.

Temperature-Dependent Sex Determination

Sex determined by environmental temperature during development.

Prader-Willi Syndrome

Condition due to paternal gene deletion on chromosome 15.

Angelman Syndrome

Condition due to maternal gene deletion on chromosome 15.

Queen Bees

Genetically identical, but express different genes due to diet.

Eukaryotes

Organisms with complex cells containing a nucleus.

Prokaryotes

Simple organisms without a nucleus, fewer genes.

Non-coding RNA

RNA molecules that do not code for proteins.

Gene Complexity

Eukaryotes have more complex genomes than prokaryotes.

Junk DNA

Non-coding DNA with no known function.

DNA Replication

Copying genetic information in cells.

Leading Strand

Synthesized continuously during DNA replication.

Lagging Strand

Synthesized discontinuously with Okazaki fragments.

Okazaki Fragments

Short nucleotide stretches formed on lagging strand.

DNA Polymerase III

Enzyme synthesizing new DNA in 5' to 3' direction.

Helicase

Unzips DNA double helix into single strands.

RNA Primer

Initial RNA segment for DNA synthesis initiation.

Primase

Enzyme creating RNA primer for DNA replication.

Ligase

Seals gaps between Okazaki fragments.

Topoisomerase

Relieves stress from unwinding DNA strands.

Telomere

DNA segment protecting chromosome ends from degradation.

Telomerase

Enzyme adding telomeres to chromosome ends.

mRNA

Messenger RNA for protein synthesis.

tRNA

Transfers amino acids to mRNA codons.

rRNA

Forms part of ribosomes for protein synthesis.

Transcription

Synthesizing RNA from a DNA template.

RNA Splicing

Removing introns and reconnecting exons in mRNA.

Exons

Protein-coding regions of the genome.

Introns

Non-coding regions in pre-mRNA.

Translation

Synthesis of proteins from mRNA sequence.

Point Mutation

Single nucleotide change causing substitution, insertion, or deletion.

Frameshift Mutation

Shifts reading frame of RNA transcript.

Silent Mutation

Codon change does not alter amino acid.

Missense Mutation

New codon encodes a different amino acid.

Nonsense Mutation

Codon change results in a premature stop codon.

Wild Type

mRNA sequence without any mutation.

Plasmids

Small, circular DNA molecules in bacteria.

Lac Operon

Operon for lactose processing in prokaryotes.

Trp Operon

Operon for tryptophan synthesis in prokaryotes.

Operons

Gene clusters controlling transcription in prokaryotes.

Conjugation

DNA transfer via cell-to-cell contact in bacteria. Pilus (bridge) between bacteria is formed

Transformation

Uptake of free DNA from surroundings by a competent bacterium.

Transduction

DNA transfer via bacteriophage infection. EX: Virus that infects bacteria.

Genome

Complete genetic information of an organism.

Transcriptome

All RNA molecules produced by a cell.

Proteome

Complete set of expressed proteins in an organism.

Post-transcriptional processing

Adding 5' cap to 5' end and poly-A tail to 3' end of mRNA for stability

Initiation

1st step in transcription: RNA polymerase attaches to promoter region and unzips DNA into 2 strands

Elongation

2nd step in transcription: RNA polymerase synthesizes RNA nucleotides using one DNA strand as template

Termination

3rd step in transcription: RNA polymerase reaches a special sequence, detaches from DNA, and disassembles from complex

Locus

A gene's location within a genome

Gene

A basic unit or sequence of genetic material that encodes a trait

Homozygous

Carrying the same alleles on each homologous chromosome

Hemizygous

Having only one copy of a gene instead of two (e.g., sex chromosomes of males are XY)

Phenotype

The set of observable characteristics in an individual resulting from the expression of genotype (e.g., Genotype Aa can produce a brown eye phenotype while genotype aa can produce a blue eye phenotype)

Allele

A variant form of a gene

Wild type

Normal version of an allele

Mutant

An allele with an altered DNA sequence

Heterozygous

Carrying a copy of the recessive allele on one of the homologous chromosomes and a copy of the dominant allele on the other chromosome (e.g., Aa)

Homologous chromosomes

A pair of chromosomes (1 maternal, 1 paternal) that contain the same genes in the same locations

Genotype

The alleles an individual carries (e.g., Aa)

Mendel's Laws of Inheritance

Principles that describe how traits are inherited through generations

Law of Segregation

Pairs of alleles are separated when gametes are formed

Test Cross

A genetic cross between a homozygous recessive individual and an individual in question to determine the latter's genotype for a given trait