Genetics Flashcards
what does DNA stand for?
deoxyribonucleic acid
what are the four base in DNA?
Adenine
Thymine
Guanine
Cytosine
draw a diagram of a section of DNA?
what is the definition of chromosome ?
a single chain of DNA that has been coiled up into a thread like structure
Define the term gene?
a specific section within DNA which codes for a specific protein
what are introns ?
non coding genes that regulate gene expression
what are exons ?
coding genes for DNA
what is semi conservative replication ?
the original double stranded will divide into two parent stands and then join with a new strand
what is the process of unwinding ?
DNA helicase breaks the hydrogen bonds between the nucleotide
the point after which the strands are separated is known as the replication fork
what does DNA polymerase do ?
collect nucleotides and matches them with the complimentary pairs on the parent strand running a 5-3 prime direction
what is the leading strand ?
the strand that is replicating in the direction of unwinding
what is the lagging strand?
strands replicating in the reverse direction
what does Primase do?
creates short segments of primers which bind to make up the sections of DNA
what are individual section of primers called ?
Okazaki fragments
what does DNA ligase do ?
a glue that seals the nucleotides together to make a continuous strand
what is the cell cycle ?
Gap 1
Synthesis
Gap 2
Mitosis
what is the process of mitosis ?
IPMAT
what is interphase ?
cell growth
production of organelles
DNA replication
produces proteins necessary for mitosis
what is prophase ?
chromosomes condense and become visible
each chromosome is comprised of 2 chromatids
spindle fibres begin to form
nuclear membrane begins to form
what is metaphase?
chromosomes line up along the equator
what is anaphase?
spindle fibres attach to the centromeres
spindle fibre pull chromatids to opposite pole of the cell
what is telophase ?
chromatids group together
2 new nuclear membranes for
chromosomes unravel
Cytokinesis occurs
what is cytokinesis in animals ?
membranes move inwards pinching two daughter cells apart
what is cytokinesis in plants ?
cell membrane and wall is created
what is the role of DNA?
to provide the blue prints for proteins
what is different about RNA to DNA?
made of ribose sugar instead of deoxyribose
single stranded instead of double
uracil instead of thymine
normally shorter the DNA
what does transcription make ?
mRNA
what is the process of transcription?
- a small section of DNA is unwound and the hydrogen bonds are broken by helicase to expose the nucleotides
- RNA polymerase goes along and picks up free nucleotides and binds it to the complimentary base to form the mRNA
- RNA polymerase and the mRNA detaches whilst the DNA zips back up
-mRNA exits the nucleus through a nuclear pore.
what prime does RNA polymerase run and why ?
3-5 prime
so add RNA nucleotides instead of DNA nucleotides
where does RNA polymerase start and stop?
Promoter sequence
Terminator sequence
what is the methylated cap?
- an alter nucleotide that binds to the 5’ end
-acts as a signalling molecule that can be reached by ribosomes
What is the poly A-tail?
- a sequence of many adenosines joined to the 3’ end
-help stabilise and protect the mRNA
what is splicing ?
the process of removing introns and joining exons together
what is alternating splicing?
controls which exons are spliced together
what is translation?
the process of creating proteins from a template in the ribosome
what is the process of translation?
-the methylated cap allow the ribosome to attache to mRNA
-the ribosome reads three nucleotides at time called a codon
-tRNA then get the anticodon that matched the codon
-the tRNA has amino acids that join together to form polypeptide chains
-the polypeptide the coils up to for proteins
what is meiosis?
the process where a single cell divide twice to form 4 daughter cells.
what is the process of meiosis?
Prophase 1
metaphase1
anaphase 1
telophase 1
cytokines 1
Prophase 2
metaphase 2
anaphase 2
telophase 2
cytokines 2
what is prophase 1 ?
-homologous chromosomes pair up
what is metaphase 1?
-homologous pairs line up on the equator
-spindle fibres attach
what is anaphase 2?
-homologous chromosomes pulled to seperate side of the cell
-chromosomes copy and go to one side
what is telophase 1?
2 haploid cells begin to formed
what is cytokinesis ?
- 2haploid cell formed
what is prophase 2?
- spindle fibres join perpendicular to the first set of chromosomes
what is metaphase 2?
-chromosomes line up along the equator
-perpendicular to the first set
what is anaphase 2?
-chromosomes split at the centromere
-sister chromatids to seperate sides
what is telophase 2?
4 haploid daughter cells
what is the definition of gene expression?
different environment can effect organisms phenotypes even if they have the same genotype
what can effect gene expression?
different food, exercise, temperature, acidity, alkalinity
what is epigenetics?
the study of chemical modifications to the gene function that are not due to DNA sequencing changes
what is a mutation?
any change to the DNA sequence
what is a spontaneous mutation ?
during DNA replication there is chance for the wrong base to be copied
what is the definition of mutagens?
a substance that induces a higher then normal rate of mutation
what are the three categories of a mutagen ?
physical
chemical
biological
what are some example of physical mutagens and what do they do to cause a mutagen ?
- radiation: causes damage to the DNA
- UV light: distort the double helix
-x-ray: breaking or severing the DNA strands
what are chemical mutagens ?
- substitution of bases with other chemical or attaching chemical makers
- causes replication error, prevents transcription, enables transcription of different proteins
what are biological mutagens?
mutations caused by invasive pathogens such as bacteria and viruses
what are the types of mutagens
neutral: no affect to the coded product
deleterious : stop or alter the production of the protein
what is a point mutation ?
a change in DNA where only one nucleotide is altered
what are the types of point mutations ?
- silent
- neutral
- missense
- nonsense
what is a substitution mutation?
when one nucleotide is replaced by another
what is a silent mutation?
no change has occurred to the codon
what is the neutral mutation ?
a change has occurred but it still codes for the same amino acid
what is a missense mutation?
a mutation that has occurred resulting in a different amino acid being formed
what is a nonsense mutation?
when the mutation causes a new stop codon to be formed
what is an insertion ?
the adding of an extra base
what is deletion ?
the removal of a base
what are some chromosomal mutations?
chromosomal deletion
chromosomal inversion
duplication
translocation
what is chromosomal deletion?
a section os DNA is removed
what is chromosomal inversion?
a break in a chromosome occurs and then is reattached the wrong way
what is chromosomal duplication?
a section of chromosome occurs twice
what is chromosomal translocation?
part of the chromosome breaks off and reattaches to the wrong chromosome
what are the four ways variation occurs?
mutations
crossing over
independent assortment of chromosomes
sexual reproduction
what is crossing over?
The exchange of genes from the maternal and paternal chromosomes creates new genetic combination
what is the law of independent assortment ?
Chromosomes seperate independently of each other during meiosis which creates various different chromosomal combinations
what is sexual reproduction ?
fertilisation of 2 gamete occurs randomly
what is sexual selection ?
selection arising through preference of an individual characteristics
what is co-dominance?
both alleles are observed in the organism eg roan cows
what is incomplete dominance?
when two genes are present but neither are dominant eg pink flowers
what are multiple alleles ?
when there are more then 2 alleles for any particular characteristics eg blood groups
what is sex-linked inheritance ?
characteristics that are carried on the sex chromosomes
what is monogenetic inheritance ?
when a characteristic is controlled by one pair of gene eg curly or straight hair
what is polygenetic inheritance?
controlled by more then one gene
what is transgenic organism?
organisms that have had the DNA of a different species inserted into their genome
what are genetically modified organisms?
organisms that have had their DNA modified
what are restriction enzymes?
they cut the DNA at the recognition site to remove a certain section of DNA
what are sticky ends ?
they have over hanging ends that ensure DNA is inserted the correct way
what are blunt ends?
DNA cut straight across
what is ligation?
DNA ligase joins the DNA strands together to form recombination DNA
what is recombinant DNA used for ?
the production of insulin, human growth hormone, vaccines
how are GMOS produced ?
-DNA is inserted in to a vector
- Vectors are inserted to the host cell
- host cells incorporate recombinant DNA with their own DNA
what are agrobacteriums ?
they are used to transfer foreign DNA into plants
what are transgenic organisms used for?
pesticides/herbicides
prevent breeding
control feral animals
process of oil
disease resistant crops
vaccines
what is DNA profiling ?
a technique used to compare two or more bases sequences using short tandem repeats
what are short tandem repeats?
section in DNA that are non coding that get repeated
what is the process of genetic finger printing
-extract DNA from a sample
-STRs cut into sections using restriction enzymes
- amplified using PCR
-separated fragments through gel electrophoresis
what is the process of gel electrophoresis ?
-DNA is cut up using restriction enzymes
-fluorescent dye is added into samples
-samples are added into gel wells on the negative electrode end
-electricity is through the gel allowing the negatively charged DNA to attach to the positive electrodes
-DNA is viewed under UV light which cause it to go fluorescent
what is the definition of DNA sequencing?
determining the order of the nitrogen bases that make up the DNA molecule
what is the process of DNA sequencing (Sanger method) ?
- denature the DNA
-heat up the stand to 98c - annealing the primer
-adding primers and reducing the temperature to 50c to allow primer to join to the single strand of DNA - synthesise the strand
-temperature is increased to 60c allowing the polymerase to synthesise the complementary base until a terminator base is added - denaturing
-temperature is increased to 96c to seperate the synthesised DNA from the template - cycles
-repeat step 1-4 util there are enough strands - fragments separated by gel electrophoresis in a cepillary tube
-smaller fragment reach the end first - fluorescing
-at the end, bases pass through a lazer causing them to go fluorescent to determine the terminator base
what is a terminator base?
a free nucleotide with an altered sugar that prevent a longer chain from forming it has a fluorescent tag on it to identify
when is polymerase chain reaction (PCR) used?
when there is not enough DNA to be tested
what is the process of polymerase chain reaction (PCR) ?
- denaturing
- heated to 95c
-DNA separates into 2 complimentary strands - annealing
-primers are added and cooled between 50-60c causing primer to bind to a single strand of DNA - synthesis
-DNA polymerase is added and free nucleotides and heated to 72c
-DNA polymerase binds free nucleotides together to form a new section of DNA
what does DNA profiling do in agriculture ?
- disease resistant
-faster growth rate
-more quality and quantity
-tolerance to adverse conditions
what are the desirable traits of GMOs?
-resistance
-faster growth rate
-greater product quality and yield
-tolerance to adverse environmental conditions
what are the benefits to GMOs?
-improved crop productivity
-improved nutritional value
-better flavour
-fresher for longer
-less herbicides and pesticides on feed
how does DNA profiling and sequencing used in conservation ?
monitoring endangered species
assessing gene pools for breading programs
tracking change in biodiversity
quarantine
GMOs in conservation
control of disease vectors
control of feral pest
what are adverse effects of biotechnology ?
-effects non target organisms
-more rapid evolution of pesticide resistant species
-the possibility of gene flow from crop species to weed species resulting in super weeds
