S5 - Unit One Flashcards
What is the basic subunit of any nucleic acid?
A nucleotide
What is the structure of DNA nucleotides
How is the structure of a sugar phosphate backbone composed?
A chemical bond forms between the phosphate group of one nucleotide and the 3’ end of the sugar on another
What is the structure of a sugar phosphate backbone?
What holds bases together?
Weak hydrogen bonds
What are prokaryote cells?
Cells containing a single circular chromosome and smaller plasmids
What are eukaryote cells?
Cells containing linear chromosomes in their nucleus
What are examples of prokaryotes?
Bacterial
What are examples of eukaryotes?
Plants, animal, yeast
How are eukaryote chromosomes organised?
Tightly coiled and packaged around histones
Eukaryotes contain linear chromosomes in their mitochondria and chloroplasts - T or F
False
Eukaryotes contain circular chromosomes in their mitochondria and chloroplasts - T or F
True
What is the exception to eukaryote cells and why?
Yeast cells, they also contain circular plasmids
What is gel electrophoresis?
A technique which separates DNA molecules by subjecting them to an electrical current
Why is DNA replicated and when does this take place?
- To ensure all the daughter cells have the same genetic info as the parent cells amd to maintain the chromosome diploid compliment
- Before mitosis
What is a primer and its role in DNA replication?
A short strand of nucleotides which bind to the 3’ end of the template DNA strand allowing DNA polymerase to add free DNA nucleotides
What is the first stage of DNA replication?
DNA is unwound and H bonds between bases are broken to form 2 template strands
What is the second stage of DNA replication?
DNA polymerase adds free DNA nucleotides using complimentary base pairing to the deoxyribose 3’ end of the new DNA strand which is forming
How do the leading strand and lagging strand differ?
Leading - replicated continuously
Lagging - replicated in fragments
Why is the lagging DNA strand replicated in fragments?
Because DNA polymerase can only replicate in the 3’ to 5’ end
What enzyme is used in the lagging strand that isn’t in the leading strand during DNA replication and what does it do?
Ligase, joins the DNA fragments
Why is a template DNA strand needed in DNA replication?
Provides a template for the genetic code
Why is a supply of DNA nucleotides needed in DNA replication?
To produce the new strand of DNA
Why is a supply of energy needed in DNA replication?
To provide DNA polymerase with energy
Why is a DNA polymerase needed in DNA replication?
To join the complementary free DNA nucleotides to the 3’ end
Why is a primer needed in DNA replication?
To all the attachment of DNA polymerase to start replication
What is a polymerase chain reaction (PCR)?
A reaction that creates many copies of DNA outside the body
What are some uses of PCR?
- Help to solve crimes
- Settle paternity suits
- Diagnose genetic disorders
What is the temp. required for the first stage of PCR and what happens?
92-98 oC
Strands separate
What is the temp. required for the second stage of PCR and what happens?
50-65 oC
Primers bind to specific target sequence
What is the temp. required for the third stage of PCR and what happens?
70-80 oC
The heat tolerant DNA polymerase replicates the region of DNA
What are the differences between DNA and RNA?
DNA: double stranded, A-T, deoxyribose
RNA: single stranded, A-U, ribose
What are the three types of RNA?
tRNA (transfer)
mRNA (messenger)
rRNA (ribosomal)
What do each of the RNA types do?
t - carries its specific amino acids to the ribosome
m - carries a complimentary copy of DNA from the nucleus to the ribosome
r - forms the organelle: ribosome
What are the two processes involved in protein synthesis?
Transcription & Translation
What is a codon and what do they do?
A triplet of bases on a mRNA molecule
Code for a specific amino acid
Where is mRNA transcribed?
From DNA in the nucleus
Where is mRNA translated and what does it produce?
Ribosomes in the cytoplasm
Proteins
What is transcription?
The synthesis of mRNA from a section of DNA
What is the fist transcript produced called in transcription?
The primary transcript
What is the second transcript produced called in transcription?
The mature transcript
What process makes the mature transcript in transcription?
RNA splicing
Why does RNA splicing take place
To remove the regions of info. not required to make a protein
What are coding and non-coding sections of an RNA transcript called?
Coding - Exons
Non-coding - Introns
What happens after introns are removed in RNA transcription?
Exons join together, forming the mature transcript of mRNA
What can happen as a result of alternative RNA splicing?
Different proteins are expressed from the same gene
What is the genome?
The entire hereditary information encoded in the DNA of an organism
What is the genome of an organism made up of?
Genes and other DNA sequences that don’t code for proteins
What are non-coding base sequences in the genome involved in?
Regulating transcription & Transcribing some to RNA
What is the translation of mRNA?
The synthesis of a polypeptide chain (protein) using the code on mature mRNA transcript
Where does translation take place?
The ribosome
What other type of RNA is involved in translation?
tRNA
Describe the structure of tRNA.
Folded into a 3D structure due to complimentary base pairing
What part of tRNA differs between each molecule?
The amino acid they carry to the ribosome
What is an anticodon?
An exposed triplet of bases on tRNA
Describe the process of translation.
Begins at start codons and ends at stop codons. Anticodons bind to codons by complimentary base pairing. This translates the genetic code into amino acids. Peptide bonds then join the amino acids together
What determines the function of a protein?
Their shape
What are examples of proteins learned about in class?
Hormones, structural, enzymes & antibodies
What are the functions of each of the proteins learned in class?
Chemical messengers, part of the cell membrane structure, biological catalyst, defend the body against antigens
What is a phenotype determined by?
The proteins produced as a result of gene expression
What factor besides genes can influence a phenotype?
Environmental
What are multicellular organisms made up of?
A large number of specialised cells
What is cellular differentiation?
The process by which a cell expresses certain genes to produce protein characteristics for that type of cell
Where does differentiation occur?
In embryonic and tissue stem cells in animals and meristems in plants
What are stem cells?
Unspecialised cells that can differentiate and divide to self renew
What are embryonic stem cells called and why?
Pluripotent, they can differentiate into all cells
What are tissue stem cells called and why?
Multipotent, they can differentiate into all the types of cells found in a particular tissue type
What are tissue stem cells used for?
Repair, growth and renewal of the cells found in that tissue
What are therapeutic uses of stem cells used for?
The repair of damaged or diseased organs or tissues
What are examples of uses of therapeutic stem cells?
Corneal repair and regeneration of damaged skin
What are research uses of stem cells?
Used as model cells to study how disease develops or in drug testing
Why is it unethical to use embryonic stem cells in research or therapeutic uses?
Because it destroys potential life
What are meristems?
regions of unspecialised cells in plants that can divide and/or differentiate
What are mutations?
A spontaneous change in DNA which results in no proteins or different proteins being synthesised
What are mutagenic agents and what are examples of them?
Factors that speed up the rate of a mutation.
Chemicals and exposure to radiation
What are the types of single gene mutations?
- Substitution
- Deletion
- Insertion
(S.I.D)
What are the definitions for each of the single gene mutations?
- When one nucleotide is swapped for another
- The addition of a nucleotide
- When a nucleotide is removed
Out of the three single gene mutations, which one is different to the rest and why?
- Substitution
- It is a point mutation and so only affects one codon and amino acid
What are the two types of single gene mutations that are frameshift mutations and what does this mean?
- Insertion and deletion
- It affects all the codons and amino acids after the mutation
What is a missense mutation?
A mutation that results in one amino acid being swapped for another
What is a nonsense mutation?
A mutation that results in a premature stop codon being produced resulting in a shorter protein
What are splice site mutations?
When introns are retrieved and / or exons are lost in the mature transcript
What does a chromosome structure mutation involve?
The breakage of one or more chromosomes
What are the types of chromosome structure mutations?
- Translocation
- Inversion
- Duplications
- Deletion
(T.I.D.D)
What is the definition of a deletion chromosome structure mutation?
When a section of a chromosome is removed
What is the definition of a duplication chromosome structure mutation?
When a section of a chromosome is added from its homologous partner
What is the definition of a inversion chromosome structure mutation?
When a section of a chromosome is reversed
What is the definition of a translocation chromosome structure mutation?
When a section of a chromosome is added to another chromosome that is not it’s homologous partner
What is evolution?
The changes in organisms over generations as a result of genomic variations
What is natural selection?
A non-random increase in frequency of DNA sequences that increase survival and the non-random reduction in the frequency of harmful sequences
What are the types of selection (excluding natural)?
- Disruptive
- Stabilising
- Directional
(D.S.D)
What is vertical transfer?
When DNA is inherited from parents to offspring as a result of sexual or asexual reproduction
What is horizontal transfer?
When prokaryotes exchange genetic material between individuals of the same generation
What is a species?
A group of organisms that do not normally interbreed with other groups and are capable of interbreeding to produce fertile offspring
What is speciation?
The formation of a new biological species by evolution as a result of: isolation, mutation, selection
What are the two types of speciation and what are the differences?
- Allopatric: occurs when the gene flow between 2 or more subpopulations is prevented by geographical barriers
- Sympatric: Occurs when 2 or more subpopulations live in close proximity in the same environment but still become genetically isolated
What is genomic sequencing?
When the sequence of DNA nucleotide bases can be determined for individual genes and entire genomes
Computer programs can be used for what in genomic sequencing?
Identifying base sequences by looking for sequences similar to known genes
What is required to compare sequence data and what is it known as?
- Computer and statistical analysis
- Bioinformatics
What is phylogenetics?
The study of evolutionary history and relationships by using gene sequences to study evolutionary relatedness among different groups of organisms
What can phylogenetic trees help show?
That the further apart two species are, the more distantly they are related and vise versa
What are the tree domains of life?
- Bacteria
- Archaea
- Eukaryotes
What has been used to determine the sequence of events in the evolution of life?
Sequence data and fossil evidence
What is the order of events of the evolution of life?
Evolution of:
- cells
- last universal ancestors
- prokaryotes
- photosynthetic organisms
- eukaryotes
- multicellular organisms
- animals
- vertebrates
- land plants
What is pharmacogenetics?
The use of genome info. in the choice of drugs
