Chapter 6 : DNA & Gene Expression Flashcards
What is DNA?
It is a molecule carried by all living organisms in almost every cell in their body. It contains information for the function of all. It is unique to each and also an individual identifier.
What is the structure of DNA?
Double helix formed of 2 sugar-phosphate backbones spiral around each other. Each bases stick from sugar molecule.
What is a nucleotide?
Unit of DNA molecule composed of phosphate, sugar and nitrogen.
What are the nitrogen-containing bases?
A-T, G-C
What is a genome?
An organism’s complete set of DNA
Also in nucleus of eukaryotes
What is a chromosome?
one or more unique pieces of DNA packed with protein
What is a gene?
A specific sequence of DNA
What is the difference in DNA shape in eukaryote vs prokaryote?
Eukaryote: linear
Prokaryote: circular
How is determined the meaning of gene?
By DNA sequence
What are alleles?
Different versions of gene that code for the same feature.
What are traits?
Any single characteristic or feature of organism.
How many alleles do human carry?
2: 1 from mom, 1 from dad. Can be same of different
What is genotype?
Based on DNA sequence, it is like an instruction book.
What is a phenotype?
It is the different forms of traits that are influenced by the genotype and environment.
How many % of DNA is coded for protein for human?
2%
Genes make up how many % of DNA for bacteria and viruses?
90% and +
What are the 3 different non-coding DNA?
Intron: non-coding DNA with gene (links coding DNA)
Exon: Coding region of gene
Intergenic region: non-coding DNA between genes (junk DNA)
What is gene expression?
The process by which genetic information used to synthesize gene product.
What is the process of gene expression?
DNA (genetic archive) transcript to RNA (working copy of gene) translate to protein (gene product)
Transcription in nucleus and translation in cytoplasm
What is transcription?
The gene’s sequence is copied from DNA to a go-between molecule called RNA.
mRNA is synthesized based on DNA info.
Takes place in nucleus
DNA is template for RNA synthesis A –> U, T –> A, etc.
What is translation?
Gene’s sequence is now encoded in mRNA which directs product of protein
What is the difference between DNA and RNA?
1 RNA molecule = 1 info for 1 gene vs DNA info for thousands of genes
RNA smaller
What is messenger RNA (mRNA)?
Product of transcription
What is transfer RNA (tRNA)?
Transport amino acid to ribosomes
What is ribosomal RNA (rRNA)?
Structural part of ribosomes.
What is RNA polymerase?
Enzyme that synthesize an RNA molecule from DNA template.
What is the structure of a gene?
Beginning marked with promoter sequence where RNA polymerase bonds and ends by terminator sequence where RNA polymerase is released.
How does transcription work?
Initiation: RNA polymerase binds to promoter sequence
RNA synthesis: synthesize using DNA as template
Terminator: released when it reaches the terminator sequence
How is RNA edited?
Cap and tail are added to the ends of mRNA and then the introns are removed and exon are joined together creating the coding sequence. Then exits nucleus in cytoplasm
How does translation happen?
It takes place in ribosome and the polypeptides (proteins) are synthesized using the info in mRNA
What is a codon?
It is a combination of 3 nucleotides that specify one amino acids. There is 64 different codons. It is a dictionary of genetic code. One amino acid can be specified by many codons.
What does the start of a codon?
It specifies the start of translation only one codon. It also codes for an amino acid methionine (Met)
What does the stop of codons?
Specify the end of translation. 3 stop codons. No amino acids are specified. Eg: UAA, NAG, UGA
How does tRNA work?
Anticodon is complementary to mRNA codon. tRNA carries the amino acid methiodine.
What are the 3 different stages of translation?
Initiation: ribosome is assembled at the start of codon.
Elongation: amino acids are added one by one
Termination: ribosome subunits are released when reach the stop codon. mRNA used to make more proteins.
How do cells evolve?
Start with one cell but develop in many different types of cells with different shapes and functions because of gene regulation
What are the different roles of these cells: red blood cells, plasma cells, neuron.
Red blood: transporting oxygen
Plasma cells: antibody production
Neuron: communication
What is gene regulation?
Process of turning on and off the level of gene expression. Gene expression is induced when and where the gene is needed. Each gene is equipped with on and off controls and fine tuning machineries at different steps. The main control point is at the transcriptional level.
What are some gene regulation examples?
Activator proteins promote transcription: initiates or speeds up gene expression.
Repressor proteins inhibit transcription: slows or blocks gene expression
mRNA can be degraded rapidly
Translation can be promoted or inhibited
What are the causes and consequences to mutation?
It is the alternation to the sequence of bases in DNA. It may be detrimental or rarely beneficial. Neutral mutation have no positive or negative effects. Mutations are essential to evolution.
What are the pro and con to mutation?
Con: can cause inherited disorders or cancer.
Pro: can create new forms that are necessary to evolution
What is spontaneous mutation?
Changes that happen when the DNA duplicates during the cellular respiration. Most mistakes will be repaired but some remains
What is mutagens?
Mutagens will increase the chances to develop cancer. Eg: smoking, UV light, radiation, etc.
What are the 3 chief causes of mutation?
Spontaneous mutation: accident when duplicated
Radiation-induced mutations: radiations with enough energy that can disrupt the atomic structure of chromosomes. Eg: UV and x-rays
Chemical-induced mutations: chemicals react with atoms. Eg: cigarettes.
What is the difference between somatic and gremlin mutations?
Somatic: mutation in somatic or body cells. Doesn’t affect genetic and can’t cause cancer.
Germline: Inherited and occurs in gametes or sex cells. Most of them cause cancer.
What are the impacts of mutation on defective enzymes?
- Creates non-functioning protein.
- Don’t catalyze reaction as they would normally.
- Molecules that would have been transformed will accumulate
- Accumulating chemical = sickness or death
What are some results of defective enzymes?
Lactose intolerence, ADHD
