Biology Lecture 2
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A series of DNA nucleotides that generally code for the production of a single polypeptide or mRNA, rRNA, or tRNA
_____________ have multiply copies of some genes, while __________ have only one copy of each gene.
The entire DNA sequence of an organism is known as __________. There are between 26000 and 38000 genes in human's
The Central Dogma of gene expression is that DNA is transcribed to ___________, which is then translated to amino acids forming a _____.
Name the four nitrogenous bases that exist in DNA
adenine, cytosine, thymine, guanine
adenine and guanine are two ring structures called _______
Cytosine and thymine are single ring structures called ______.
Each nucleotide is bound to the next by this type of bond between the third carbon of one deoxyribose and the phosphate backbone of a single strand of DNA with a 5' to 3' directionality.
Adenine is bonded to thymine with ___ hydrogen bonds
cytosine is bonded to guanine with _____ hydrogen bonds
DNA replication is this meaning that when a new double strand is created, it contains one strand from the original DNA and one newly synthesized strand
Replication proceeds in both directions from an origin. Each direction produces a leading and a lagging strand. This process is _______
What is the enzyme that builds the new DNA strand?
It cannot initiate a strand from two nucleotides but can only add nucleotides to an existing strand. Requires RNA primer to get started.
remember: "ase" = enzyme
Reading DNA is like padding upstream from _________. Once the DNA is read, synthesizing DNA is downstream, from __________
name the five steps in DNA replication:
- 1. Helicase unzips the double helix
- 2. RNA Polymerase builds a primer
- 3. DNA Polymerase assembles the leading and lagging strands
- 4. the primers are removed
- 5. Okazaki fragments are joined
The lagging strand is made from a series of disconnected strands called
This moves along the lagging strand and ties the Okazaki fragments together to complete the polymer
The process of replication in which the formation of one strand is continuous and the other fragmented is called
List the differences between DNA and RNA
DNA is made from deoxyribose; RNA is made from ribose. DNA is double stranded; RNA is single stranded. DNA has thymine; RNA has uracil. DNA is produced by replication; RNA is produced with transcription. In animals, DNA is only in nucleus and mitochondrial matrix; RNA is also in the cytosol. There is only one major DNA; but three major RNA
This RNA delivers the DNA code for amino acid to the cytosol where the proteins are manufactured.
mRNA (messenger RNA)
This RNA combines with proteins to form ribosomes
rRNA (ribosomal RNA)
This is the cellular complexes that direct the synthesis of proteins
This RNA collects amino acids in the cytosol and transfers them to the ribosomes for incorporation into a protein
tRNA (transfer RNA)
All RNA is manufactured from a DNA template in a process called ____________.
It requires a promoter
This is a spot on the DNA that tells RNA polymerase where to begin transcription.
This is a short piece of RNA that jump starts DNA replication
The beginning of transcription is called
During this second step of transcription, RNA polymerase transcribes only one strand of the DNA nucleotide sequence into a complementary RNA nucleotide sequence
This final step in transcription requires a special termination sequence and special proteins to dissociate RNA polymerase from DNA
For all cells, most regulation of gene expression occurs at the level of transcription via proteins called _______ and _________. They bind to DNA close to the promoter, and either activate or repress the activity of RNA polymerase.
activators and repressors
The genetic unit usually consisting of the operator, promoter, and genes that contribute to a single prokaryotic mRNA is called ______
The initial mRNA nucleotide sequence arrived at through transcription is called the ________
This serves as an attachment site in protein synthesis and as a protection against degradation by exonucleases
the 5' cap
the 3' end is polyadenylated with a _____, also to protect it form exonucleases
a poly A tail
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