Exam 2 Flashcards
(64 cards)
What is DNA?
Nucleic acids that are used to store and transfer information.
- DNA is like a hard drive
- RNA is like RAM
What are the monomers of DNA?
Nucleotides
Each contains: - Deoxyribose (5-carbon sugar)
- Phosphate group
- A nitrogen-containing base (Adenine, Guanine, Thymine, Cytosine)
What is the Structure of DNA?
Two nucleotide strands held together by hydrogen bonds
How did the experiments of Griffith, Oswald and Avery, and Hershey and Chase change scientists’ understanding of the role of DNA?
Griffith: his experiment laid the foundation for scientists to clarify the transforming principle in the molecular nature of this substance
Oswald & Avery: Their experiment was the first to suggest that the transforming principle from Griffith’s experiment was DNA and not proteins as previously thought by scientists
Hershey and Chase: Their experiment provided compelling evidence that DNA carried hereditary material and not proteins.
Together, these experiments shifted the prevailing view in biology from proteins to DNA as the primary molecule for genetic information storage and transfer.
What did Chargaff, Franklin, Watson, and Crick contribute to our knowledge of DNA’s structure?
Chargaff showed that the amount of Adenine always equals amount of thymine and amount of guanine always equals amount of cytosine
Franklin concluded that DNA was some sort of helix
Watson and Crick put the information from both experiments into a coherent structure and concluded that DNA is a double helix with ATCG bases that line up and pair correspondingly
How is DNA replicated?
- Hydrogen bond b/w two strands are boken.
- each strand then serves as template for new strand
- They are then replicated and each strand becomes half old and half new
What enzymes are responsible for DNA replication and repair?
DNA Polymerase attaches complementary nucleotides
DNA ligase fills in gaps
What is the difference between the structure of DNA and RNA?
DNA is a double-stranded helix while RNA is typically single-stranded.
What are the different types of RNA and their role in gene expression?
mRNA: carries the genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm, serving as a template for protein synthesis
tRNA: deliver amino acids to ribosomes in the order specified by the mRNA
rRNA: reads the mRNA and acts as an enzyme to form peptide bonds b/w amino acids, assembling them into a polypeptide chain
What is the purpose of gene expression (The Central Dogma of Biology)?
The primary purpose of gene expression, as outlined by the Central Dogma, is to convert the genetic information encoded in DNA into functional molecules, primarily proteins, that carry out the vast majority of cellular functions. The process ensures cells can grow, reproduce, and respond to environmental changes.
What are the steps of gene expression?
Replication: the process by which DNA makes an exact copy of itself, ensuring that genetic information is passed on during cell division.
Transcription: a specific segment of DNA (a gene) is used as a template to synthesize a corresponding RNA molecule. This RNA molecule, called messenger RNA (mRNA), carries the genetic information from the DNA in the nucleus to the cytoplasm.
Translation: The mRNA serves as a template for protein synthesis. In the cytoplasm, ribosomes “read” the sequence of mRNA codons, and tRNA molecules bring the appropriate amino acids to the ribosome to build the protein.
Where do each steps of gene expression take place?
Replication and transcription takes place in the nucleus. Translation takes place in the cytoplasm
What is a ribosome and what is its role in translation?
Ribosomes “read” the sequence of mRNA codons, and tRNA molecules bring the appropriate amino acids to the ribosome to build the protein.
What is the role of tRNA in translation?
transfer RNA (tRNA) delivers amino acids to ribosomes in the order specified by mRNA
What is a codon and how many codons are there?
A codon is a sequence of three nucleotide bases in mRNA (messenger RNA) that corresponds to a specific amino acid or a start/stop signal in protein synthesis; 64 codons
What is the start codon and which amino acid does it code for?
AUG; Methionine
What is a polysome, and how does it speed up the process of protein production?
Cluster of ribosomes that are simultaneously translating an mRNA
What is the difference between a substitution mutation and an Indel?
Substitution: a single base-pair changes. can be silent, missense, or nonsense
Insertions and Deletions (Indels): one or more base pairs are lost from or inserted into the DNA. Can cause frameshift
What are some of the causes of mutations?
- most result from unrepaired DNA polymerase errors during DNA replication
- some result from transposable element activity, or exposure to radiation or chemicals
What is the purpose of mitosis and meiosis?
to create more cells for growth, damage repair, or reproduction
How do mitotic daughter cells compare to the mother cell?
The (2) daughter cells are genetically identical
How do meiotic daughter cells compare to the mother cell?
4 daughter cells that are genetically different
What is the difference between a chromosome and a chromatid?
A chromosome is a package (set) of DNA molecules. Chromatids are the individual DNA molecules.
What are the stages in the mitotic cell cycle?
Interphase-stage at which cells carry out typical function
- G1, S, G2
Mitosis- cell replication
- Prophase, Metaphase, Anaphase, Telophase
Cytokinesis
