U1 Lecture 6 Flashcards
- List the 4 nucleotides involved in DNA and RNA and know their organization - Define chromosome, gene, codon, transcription, translation, exon, intron, and alternative splicing - Compare and contrast the characteristics and functional significance of transcription and translation - Describe the regulation of gene expression, incorporating use of the concepts associated with transcription factors, promoters, and RNA polymerase - List in chronological order the 4 phases of mitosis. Discuss the p
Structure of the nucleus
- Nucleus
- Chromatin
- Nuclear envelope
- Nuclear pore
- Polyribosome
- Rough endoplasmic reticulum
What is the genetic material found inside of the nucleus?
Nucleic Acid
Functions of the nucleus
- Stores information (DNA)
2. Coordinated cell’s activities including growth, metabolism protein synthesis, and reproduction/ cell division
Nucleic Acid components
- Sugar
- Phosphate
- 1 of 4 different nitrogenous bases
Nitrogenous Bases
- Adenine
- Guanine
Thymine in DNA or 3. Uracil in RNA - Cytosine
Terminology of nucleic acid
- Nucleoside = base + sugar
- Nucleotide = nucleoside + phosphate
- Nucleic acid = sequence (strands or polymers) of nucleotides
Define codon
‘Triplet’ of 3 bases that represents one of 20 different amino acids
A series of bases represents a primary protein sequence
Define gene
a sequence (of codons) that represents (encodes) a single polypeptide (protein)
Base Pairs
- A double bonds to T
- C triple bonds to G
Coping DNA
Cells pull apart and match complementary bases to make new strands
Information in DNA
The ‘double helix’ of DNA contains two complementary strands which contains…
- info encoded in the other strand
- info concerning protein structure
Terminology of chromosomes
-Nucleosome = DNA double helix wrapped around a histone (protein)
- Chromatin = chain of nucleosomes
- Chromatin fiber = netting of chromatin
- Chromosome = weaving of chromatin fiberinto an ‘X’ shape
Chromatid = the arms and legs of the ‘X’ shaped chromosome
Centromere = the center point of the chromosome
Chromatin vs. Chromosome
Chromatin = dispersed DNA, the typical condition of DNA
Chromosome = condensed DNA, when cell is dividing
Steps of protein synthesis
- Transcription
2. Translation
Transcription
- Occurs in the nucleus
- Produces messenger RNA (mRNA) from DNA
- Synthesis of a complementary strand of RNA using the base sequence of DNA as a template
- Alternative splicing of exons can produce distinct mRNAs from one gene
Translation
- Occurs in cytoplasm
- Involves mRNA, rRNA, tRNA
- Produces protein
Define exon
A segment of a DNA or RNA molecule containing info coding for a protein or peptide sequence
Define intron
A segment of a DNA or RNA molecule that does not code for proteins and interrupts the sequence of genes
Define alternative splicing
A regulated process during gene expression that includes or excludes particular exons from the final messenger RNA
Steps of translation
- Initiator tRNA attaches to a start codon
- Large and small ribosomal subunits join to form a functional ribosome and initiator tRNA fits into position on the ribosome
- Anticodon of incoming tRNA pairs w next mRNA codon beside initiator tRNA
- Amino acid on initiator tRNA forms a peptide bond w amino acid beside it
- tRNA leaves the ribosome; ribosome shifts by one codon; tRNA binds to newly exposed codon; steps 3-5 repeat
- Protein synthesis stops when the ribosome reaches stop codon on mRNA
Define gene expression
The process by which the heritable info in a gene (the sequence of DNA base pairs) is made into a functional gene product like protein or RNA
Two main stages of gene expression
- Transcription***
2. Translation
Sites of gene expression during transcription
- Promoter = DNA sequence ‘upstream’ to the start of a gene to which RNA polymerase binds
- Transcription factors = roteins that bind to the promoter to augment binding of RNA polymerase
- ** Promoter regulation is a mechanism for regulating gene expression
The phases of the cell cycle
- G1 Phase
- S Phase
- G2 Phase
- Mitotic (M) Phase
G1 Phase
- Cell metabolically active
- Duplicated organelles and cytosolic components
- 8-10 hours
S Phase
DNA and centrosome are replicated
- 8 hours
G2 Phase
- Cell growth continues
- Enzymes and other proteins are synthesized
- 4-6 hours
Phases of Mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
Define prophase
Condensation of DNA into chromosomes
Define metaphase
Alignment of chromosomes along a center line or plane (the ‘metaphase plate’
Define anaphase
Separation of ‘sister chromatids’ to daughter cells
Define telophase
Formation of two new nuclei
