Viruses Flashcards
(32 cards)
How does the DNA move between bacteria? - horizontal gene transfer - HGT
- Transformation
- Conjugation
- Transduction
What does Transformation refer to when it comes to DNA moving between bacteria?
Bacteria taking free-floating DNA from their environment
What does Conjugation refer to when it comes to DNA moving between bacteria?
One bacterium directly transfers DNA to another through physical contact
What does Transduction refer to when it comes to DNA moving between bacteria?
Viruses carry DNA from one bacterium to another
How do genes move between species? - inter-kingdom gene transfer (an example is being given for this question)
Type of bacteria (Agrobacterium tumefaciens) that can infect plants and when it does, it injects some of its own DNA into the plant’s cell causing the plant to grow tumour-like lumps called crown galls
How can Agrobacterium tumefaciens be used in a positive way?
By taking the part of the bacteria’s DNA called Ti plasmid and swap out the harmful genes for helpful ones - like genes that make a plant resist bugs or grow faster
- then they let the bacteria transfer the new, edited DNA into the plant (this is one of the ways scientists genetically modify plants
What are jumping genes (transposable elements)?
inside the DNA, there are chunks known as ‘jumping genes’ which are pieces of genetic code that can move around to different places within a genome
How much of the DNA is made up of jumping genes?
40%
How much of the DNA is made up of jumping genes in corn?
up to 80%
How many types of jumping genes are there?
2 types:
1. Transposons
2. Retrotransposons
What is a Transposons?
cut themselves out of one spot in the DNA and jump to a new spot
What are Retrotransposons?
‘copy and paste’ tools, firstly turning themselves in RNA which is a temporary copy, then use a special enzyme called reverse transcriptase to turn the RNA back into DNA - inserting this copy into a new place in the genome
Why are they called retro Transposons?
due to working similarly to retroviruses such as HIV which also use reverse transcriptase
What is a virus’s structure (morphology)?
- not considered alive due to having no metabolism
- made of a caspid (protein shell) that protects their genetic material
- covered in an envelope (from the host cell)
How large are mimiviruses?
large, up to 1 micron in size
What types of genetic material are present in viruses?
- ssRNA = single stranded RNA ( +/- strand)
- dsDNA, ssDNA
What are some examples of viruses?
Yellow fever, smallpox, measles and tomato spotted wilt viruses - all viral diseases
- or plaque which is a clear area on a Petri dish where viruses have killed bacteria
Smallpox and The Columbian exchange - impact
- smallpox (variola) : airborne virus with double-stranded DNA
- caused up to 30% death rate in general, but over 90% in indigenous Americans
- contributed to the fall of Inca and Aztec empires
What are the virus types based on genetic material?
7 clases
Class I virus including type and example
Type: Double stranded DNA
Ex: Smallpox and Herpes
Class II virus including type and example
type : single-stranded DNA
ex: parvovirus
Class III virus including type and example
Type: Double-stranded RNA
Ex: Rotavirus
Class IV virus including type and example
Type: single stranded RNA + strand
Ex: yellow fever, hepatitis A/C, Rubella
- Works like mRNA, can be used directly by cells to make proteins
Class V virus including type and example
Type: single stranded RNA (- strand)
Ex: measles, mumps, rabies and ebola
- must be copied into +RNA before making proteins
