Genetics Part 1 Flashcards
What do DNA polymerases III do?
- Adds new bases to the new DNA chain
- Proofreads the chain for mistakes
Define mutation.
A permanent, inheritable change in genetic information
What is a gene?
A specific segment of DNA that codes for one functional product
What is genetics?
Study of inheritance (heredity) in living organisms
What does genetics cover?
- Transmission of biological traits
- Expression of traits in organisms
- Structure & function of genetic material
- Changes in genetic material
What is a genome?
Sum total genetic material of an organism
How is genetic material primarily organized in cells?
In the form of chromosomes; also as plasmids or in organelles
What is a eukaryotic chromosome composed of?
DNA wrapped around histone proteins
Where are eukaryotic chromosomes found?
In the nucleus
How do eukaryotic chromosomes appear?
diploid, haploid (linear appearance)
How are bacterial chromosomes organized?
- DNA condensed with histone-like proteins
- usually one or a few circular chromosomes
What is the difference between diploid and haploid chromosomes?
Diploid contains two sets of chromosomes; haploid contains one set
What are structural genes?
Genes that code for proteins
Genes for RNA machinery
help in protein production
Regulatory genes
control gene expression
What is the genotype?
Sum of all gene types; organism’s complete genetic makeup
What is the phenotype?
Expressed traits resulting from the genotype
What are the components of a nucleotide?
- Phosphate
- Deoxyribose sugar
- Nitrogenous base
Fill in the blank: The sugar-phosphate backbone attaches in a repetitive pattern of two phosphates in the _______ direction.
5′ to 3′
What are the base pairs in DNA?
- A-T (Adenine-Thymine)
- G-C (Guanine-Cytosine)
What is semiconservative replication?
- 30+ enzymes involved
- Two daughter molecules are identical to the parent strand
- Each daughter molecule has one original and one new strand
What is the role of helicase in DNA replication?
Unzipping the DNA helix
What does DNA polymerase I do?
- removing primer
- closing gaps
- repairing mistakes
What is the function of ligase in DNA replication?
- Final binding of nicks in DNA during synthesis and repair
- links Okazaki fragments on the lagging strand
Gyrase/ Topoisomerase I and II
helps untangle DNA supercoils
Primase
synthesizing RNA primer
True or False: DNA replication involves two daughter molecules that are identical to the parent strand.
True
What is transcription?
Master code of DNA that is first used to synthesize an RNA molecule
What is the process of translation?
Transcribed RNA is used to produce protein
Where does translation occur?
in ribosomes
70S ribosomes are found in
- bacteria
- mitochondria
- chloroplasts
80S ribosome are found in:
eukaryotes
Function of small ribosomal subunit?
binds to the 5’ end of mRNA
Function of the large ribosomal subunit?
supplies enzymes for making peptide bonds
What are the exceptions of the transcription and translation pattern?
- RNA viruses convert RNA to other RNA
- Retroviruses convert RNA to DNA
How does RNA differ from DNA?
- RNA is single-stranded
- Contains ribose (not deoxyribose)
- Uses Uracil (U) instead of Thymine (T)
- RNA can form secondary and tertiary levels of complexity (tRNA, rRNA)
What is the function of messenger RNA (mRNA)?
Carries genetic instructions
What is the role of transfer RNA (tRNA)?
Brings amino acids to ribosome
What does ribosomal RNA (rRNA) do?
Component of ribosomes
Regulatory RNAs includes:
- Micro RNAs
- Anti-sense RNAs
- Riboswitches
- Small interfering RNAs
Primer RNAs
operative in both bacterial and eukaryotic cells
What is a codon?
Triplet of bases that determines amino acid sequence
What is the start codon?
AUG (Methionine)
List the stop codons.
- UAA
- UAG
- UGA
What is the wobble effect?
- Some mutations do not change amino acid sequence
- Only the first two nucleotides are required to encode the correct amino acid
How does bacterial translation differ from eukaryotic translation?
Bacterial translation can begin before transcription ends
What are introns?
Non-coding sequences that are removed before translation in eukaryotic mRNA
True or False: Eukaryotic mRNA can code for several genes in a series.
False
What is the characteristic of eukaryotic genes?
Contain introns that do not code for proteins and exons that do
What is the role of regulatory RNAs?
Regulate gene function
What are ribozymes?
Made of RNA; remove unneeded sequences from other RNAs
