Unit 5

DNA Structure & Properties Contains the genetic instructions for building proteins.
DNA Structure & Properties Located in the nucleus of eukaryotic cells.
DNA Structure & Properties Almost every cell in the body has the same DNA.
DNA Structure & Properties Cells are different because they express different genes.
DNA Structure & Properties The human genome has about 3.5 billion base pairs.
Nucleotide The basic building block (monomer) of DNA.
Nucleotide Parts Phosphate group, deoxyribose sugar, nitrogenous base.
Deoxyribose Sugar The sugar found in DNA.
Ribose Sugar The sugar found in RNA.
Nitrogenous Base The part of DNA/RNA that carries genetic information.
Pyrimidines Single-ring bases: Cytosine and Thymine (Uracil in RNA).
Purines Double-ring bases: Adenine and Guanine.
Double Helix The twisted ladder shape of DNA.
DNA Backbone The sides of DNA made of alternating sugar and phosphate groups.
Hydrogen Bonds Weak bonds holding nitrogen bases together.
Antiparallel The two DNA strands run in opposite directions.
5’ End End of DNA strand with a phosphate group.
3’ End End of DNA strand with a sugar group.
Chargaff’s Rule A pairs with T, and G pairs with C.
Adenine (A) Pairs with Thymine (T) in DNA.
Thymine (T) Pairs with Adenine (A).
Cytosine (C) Pairs with Guanine (G).
Guanine (G) Pairs with Cytosine (C).
DNA Replication Process of copying DNA before cell division.
Replication Step 1 Unwinding of the DNA double helix.
Replication Step 2 Unzipping when hydrogen bonds break apart.
Replication Step 3 DNA Polymerase adds matching nucleotides.
Replication Step 4 Replication stops at the end of the strand.
Replication Step 5 New DNA strands rewind into double helices.
DNA Polymerase Enzyme that adds complementary nucleotides during replication.
Semi-Conservative Replication Each new DNA molecule has one old strand and one new strand.
Chromatin Loose, unwound DNA used during normal cell activities.
Chromosome Tightly coiled DNA visible during cell division.
Human Somatic Cells Contain 46 chromosomes.
Gene A section of DNA that codes for a protein.
Sister Chromatids Two identical copies of a chromosome.
Centromere Area holding sister chromatids together.
Cell Cycle The series of events a cell goes through to grow and divide.
Interphase Longest phase of the cell cycle where the cell grows and copies DNA.
G1 Phase Cell grows and performs normal functions.
S Phase DNA replication occurs here.
G2 Phase Cell prepares for division.
G0 Phase Resting phase where the cell stops dividing.
Mitosis Process where the nucleus divides.
Prophase Chromosomes condense and nuclear membrane disappears.
Metaphase Chromosomes line up in the middle of the cell.
Anaphase Sister chromatids separate to opposite sides.
Telophase New nuclei form around chromosomes.
Cytokinesis Cytoplasm divides into two separate cells.
DNA vs RNA DNA is double stranded while RNA is single stranded.
DNA vs RNA DNA uses deoxyribose sugar while RNA uses ribose sugar.
DNA vs RNA DNA uses thymine while RNA uses uracil.
Messenger RNA (mRNA) Carries genetic instructions from DNA to ribosomes.
Transfer RNA (tRNA) Brings amino acids to the ribosome.
Ribosomal RNA (rRNA) Makes up the structure of ribosomes.
Transcription Process of making mRNA from DNA.
Transcription Location Occurs in the nucleus.
Uracil (U) Replaces thymine in RNA.
Translation Process of building proteins from mRNA instructions.
Translation Location Occurs at ribosomes in the cytoplasm.
Codon A group of 3 mRNA bases coding for one amino acid.
Peptide Bond Bond connecting amino acids together.
Start Codon AUG; signals the start of translation and codes for Methionine.
Stop Codons UAA, UAG, and UGA; signal the ribosome to stop translation.
Mutation A change in the DNA sequence.
Mutation Causes Random replication errors or environmental factors like radiation and chemicals.
Mutation Benefit Creates genetic variation for evolution.
Mutation Harm Can cause diseases or cancer.
Substitution Mutation One base is replaced with another base.
Substitution Mutation Effect Usually changes only one codon.
Nonsense Mutation A substitution mutation creating an early stop codon.
Insertion Mutation An extra base is added into the DNA sequence.
Insertion Mutation Effect Causes a frameshift that changes all following codons.
Deletion Mutation A base is removed from the DNA sequence.
Deletion Mutation Effect Causes a frameshift changing all following amino acids.
Frameshift Mutation A mutation that shifts the reading frame of codons.
Cancer Disease caused by uncontrolled cell division.
Tumor A mass of abnormal cells.
Benign Tumor Tumor that does not spread.
Malignant Tumor Cancerous tumor that spreads uncontrollably.
Carcinogens Substances or factors that increase cancer risk.
Examples of Carcinogens Alcohol, smoke, UV rays, radon.
Healthy Cells Have controlled replication and normal DNA.
Cancer Cells Replicate uncontrollably and contain mutated DNA.
Both Healthy and Cancer Cells Contain DNA and organelles and undergo mitosis.
Normal DNA Example ACG → mRNA UGC → Protein Cysteine.
Substitution Mutation Example ACT → mRNA UGA → STOP codon.
Insertion Mutation Example Adding a base shifts all codons after it.
mRNA Single-stranded RNA carrying genetic instructions.
Protein A chain of amino acids folded into a functional molecule.
Amino Acid Building block of proteins.
Ribosome Organelle where proteins are made.
Protein Synthesis Process of making proteins using transcription and translation.
Central Dogma DNA → RNA → Protein.
Complementary Base Pairing Rules determining how bases match during replication/transcription.
Cysteine An amino acid coded by UGC.
Methionine Amino acid coded by the start codon AUG.
Phenylalanine Amino acid from codon UUU.
Tyrosine Amino acid from codon UAU.
Alanine Amino acid from codon GCA.
Isoleucine Amino acid produced after an insertion frameshift example.
Cytoplasm Jelly-like area of the cell where translation occurs.
Nucleus Organelle containing DNA in eukaryotic cells.