Untitled Quiz

Genetics

• Study of genes
• Genome holds all genetic information
• Genes are DNA fragments
• DNA is a double helix
• DNA is composed of nucleotides containing A, T, C, and G bases
• DNA contains a ribose (deoxyribose) group and phosphate group linked by hydrogen bonds

Chromatin

• Chromatin is the complex of DNA, RNA, and proteins found in the nucleus of eukaryotic cells
• It condenses during cell division to form chromosomes

Genotype & Phenotype

• Genotype: The sum of all genes that encode for the characteristics of an organism
• Phenotype: Refers to expressed properties and is the manifestation of the genotype

DNA Replication

• Each daughter double helix has an original strand from the parent and a newly synthesized complimentary strand
• Replication occurs when the two strands of the double helix unwind
• Each strand serves as a template for forming a new complementary strand

DNA Replication Enzymes

• Helicase: Opens the double helix by disrupting hydrogen bonds
• Single-strand binding protein: Prevents the helix from reforming before replication
• DNA polymerase: Links nucleotide subunits to form a new DNA strand from a DNA template

Nucleic Acids and Proteins

• Genes are converted into messenger RNA (mRNA)
• mRNA is transcribed into proteins
• Genes can also be converted to ribosomal RNA (rRNA) or transfer RNA (tRNA) which then produce proteins

Gene Expression

• Gene expression is the process by which DNA is expressed into proteins
• The two stages of gene expression are transcription and translation

Transcription

• Only one strand of DNA is translated into mRNA
• This strand is called the DNA template strand
• RNA bases include C, G, U, and A (U replaces T in DNA)

Translation

• The synthesized mRNA is read in a sequence of triplets
• Every three nucleotides form one amino acid
• Amino acids are joined together to form a protein

Codons

• The table includes 64 codons
• 61 codons encode amino acids
• Codons are read in the 5’→ 3’ direction
• The AUG codon codes for methionine, acting as the start codon for translation
• UAA, UAG, and UGA are stop codons, indicating the end of the translation process

Transcription Components

• RNA polymerase: The enzyme for transcription
• Transcription factors: Proteins needed for transcription
• Promoter and terminator: DNA sequences that control transcription

Transcription steps

• Initiation: Beginning of transcription
• Elongation: RNA polymerase moves down the DNA template strand, building mRNA
• Termination: Stop codons signal the end of transcription

Translation components

• Messenger RNA: Carries the genetic code
• Transfer RNA: Carries specific amino acids
• Ribosomes: Organelle responsible for protein synthesis
• Amino Acids: Building blocks of proteins

Transfer RNA (tRNA)

• tRNA pairs a complementary anticodon with a codon
• tRNA links the codon to a corresponding amino acid
• The anticodon is read in the 3’→ 5’ direction

Ribosomes

• Ribosomes consist of two subunits:
  • A large subunit with three binding sites for tRNA
  • A small subunit with a binding site for mRNA

Poly Ribosomes

• Poly Ribosomes allow multiple ribosomes to translate a single mRNA at a time
• This creates a functional protein
• Microscopic observation shows polyribosomes

Eukaryotic Cell

• In eukaryotic cells, translation and transcription occur at different locations
• Transcription takes place in the nucleus
• Translation takes place in the cytoplasm