What is a nucleic acid?
Polymer of nucleotides
What is the function of DNA?
To code for the production of proteins.
What is Chargaff's Rule?
Proportions of A&T and G&C are the same
Describe the result of DNA replication.
Semi-conservative replication in which half of the new strands are parental and the other half daughter strands
What structures are used in DNA replication? How are they used?
-Helicase unzips parental double helix
-DNA polymerase performs base pairings
-Ligase links Okazaki fragments (lagging strand)
-Primase initiates replication
What are the differences between DNA and RNA?
-DNA uses deoxyribose, RNA uses ribose.
-DNA bases are ATCG, RNA bases are AUCG
-DNA is double stranded, RNA is single stranded
Name the three types of RNA and their function in protein synthesis
-rRNA is a protein that makes up ribosomes
-tRNA transports amino acids to ribosomes
-mRNA codes for the order of amino acids
What are the two parts of protein synthesis? What process do they complete? Where do they take place?
Transcription: Transcribes DNA sequence into mRNA (which can pass through nuclear membrane), occurs in nucleus
Translation: Translates mRNA sequence to a sequence of amino acids in the ribosomes
What is on tRNA?
Amino acid, anticodon
When does transcription begin?
When RNA polymerase binds to the promoter of a gene
What is a terminator sequence in transcription?
A genetic sequence that marks the end of a gene or operon
When does translation begin?
After the mRNA arrives at the ribosomes or transcription is finished
What is terminator sequence in translation?
A codon in mRNA that instructs the ribosome to detach itself from the mRNA (UAA, UAG, UGA)
What is the effect of a frame-shift mutation? Name two types.
Causes every codon proceeding mutation to change.
-Insertion: nucleotide is added
-Deletion: nucleotide is removed
What are the effects of point mutations?
-Silent mutation: codon is changed to a codon that codes for the same amino acid
-Missense mutation: a single amino acid is changed
-Nonsense mutation: premature termination (codon changes to stop codon)
How many nucleotides does it take to code for an amino acid? How many codons?
3 nucleotides: 1 codon: 1 amino acid
What occurs during RNA splicing in eukaryotes?
Introns are removed and exons are strung together.
Acts as an on/off switch, determines whether or not RNA polymerase can attach to promoter by presence or absence of repressor
Define: regulatory gene
Codes for production of constant amount of operon repressors so that they are available when needed
Attaches to operator and inhibits RNA polymerase from attaching
Where RNA polymerase attaches
Attaches to RNA polymerase when the gene folds, initiating transcription
When is the lac operon turned on/off? What does it produce?
In the presence of lactose, the lac operon is turned on and produces lactase.
When is the trp operon turned on/off? What does it produce?
In the absence of tryptophan, the trp operon is turned on and produces more tryptophan
Coding sequences of DNA
Non-coding, intervening sequences of DNA
Explain the process of RNA splicing, where and when does it occur?
RNA splicing strings together exons and removes introns in the nucleus, occurs after transcription but before the mRNA enters cytoplasm
What is alternative RNA splicing, how does it create two different proteins from the same DNA template in the nucleus?
Different exons from the RNA transcript are strung together to code for different proteins: different exons --> different mRNA --> different protein
What would happen if a cell would enter mitosis before S phase?
Since S phase duplicates DNA, if mitosis occurred before S phase, the daughter cells would only have half of the genetic information
What would happen if a cell would enter mitosis before G2 phase?
Since G2 phase produces the necessary organelles needed for mitosis to occur, without it, mitosis would go horribly wrong and nondisjunction would occur (no centrioles, spindle fibers, etc.)
What is a diploid cell?
A cell with two copies of genetic information/chromosomes
What is a haploid cell?
A cell with only one copy of genetic information/chromosomes
What occurs during G1 of the cell cycle?
What occurs during S phase of the cell cycle?
The DNA (chromosomes) in the cell duplicate
What occurs during G2 phase of the cell cycle?
The cell grows and prepares for mitosis, making necessary organelles for mitosis
What occurs during mitosis/cytokinesis of the cell cycle?
Parental cell is split into two identical daughter cells (cytokinesis cleaves the connection between the two cells)
Why do our cells look different and function differently?
Different cells are specialized to perform different functions
What is the relationship between a chromosome, chromatids, and homologous chromosomes?
Chromatids are the two identical parts of a duplicated chromosome. Homologous chromosomes are pairs of identical chromosomes.
What is the difference between mitosis and meiosis?
-Mitosis produces 2 haploid daughter cells
-Meiosis produces 4 diploid daughter cells
What is similar between Meiosis II and mitosis?
In anaphase of both Meiosis II and Mitosis, the sister chromatids are pulled to the poles, while in Meiosis I, homologous chromosomes are pulled apart
Describe the function of the spindle fibers during cell division.
Spindle fibers pull apart either homologous chromosomes (meiosis I) or sister chromatids (meiosis II, mitosis) to the poles of the nucleus
What is non-disjunction? Why can it be detrimental to a cell?
Non-disjunction is the absence of a separation of either homologous chromosomes or sister chromatids (during either mitosis or meiosis)