Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS1 BAMS molecules and cells > molecular biology > Flashcards

molecular biology Flashcards

You may prefer our related Brainscape-certified flashcards:
Organic Chemistry 101 flashcards
1
Q

what are nucleotides?

A

monomeric units from which nucleic acids are built
(base + sugar + phosphate)
involved in nearly all biochemical processes
- cellular energy exchanges (ADP, ATP)​
- coenzymes (NAD, FAD, CoA)​
- second messengers (cAMP) ​

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are nucleic acids?

A
  • deoxyribonucleic acid- DNA
  • ribonucleic acid- RNA

functions:
- direct synthesis of proteins
- transmit genetic information

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is a nucleoside?

A

base + sugar (NO PHOSPHATE!!)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the difference in DNA and RNA?

A

DNA- deoxyribonucleotides
RNA- ribonucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is ATP?

A
  • main biological energy store
  • produced in mitochondrion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is cAMP?

A

second messenger in action of many hormones
- Hormone binds to receptor in plasma membrane of cell​
- Adenyl cyclase stimulated​
- ↑ Adenyl cyclase activity leads to ↑ cAMP inside cell​
- cAMP acts inside cell to alter rate of one or more processes​

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the structure of DNA?

A
  • Found mainly in cell nucleus​
  • DNA backbone consists of deoxyriboses linked by phosphodiester bridges​
  • Sugar of one nucleotide joined at C-3′ (OH) to phosphate group attached to C-5′ of sugar of the next nucleotide (3′-5′ phosphodiester bonds)​
  • Bases project from sugar residues​
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what bonds hold together the two strands in the DNA double helix?

A

hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the general structure of RNA?

A

Found mainly in cytoplasm​
Same 5′─3′ backbone as DNA​
​
RNA differs from DNA:​
Uracil (U) replaces thymine (T)​
Ribose replaces deoxyribose​
Single-stranded (no base pairing)​

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is a hairpin loop?

A

local double strand formation can occur within RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the genetic code transmitted via?

A

genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the genome?

A

whole genetic information within a single cell nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the steps of protein synthesis?

A
  • In nucleus, DNA unfolds (H bonds split) to expose base pairs of template strand​
  • Transcription: RNA polymerase copies sequence of bases in template strand of DNA to produce mRNA​
  • mRNA translated by tRNA, using ribosome as a functional support (in cytoplasm)​
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe translation

A

Ribosome: small and large subunits, contain proteins and​ rRNA​
​
tRNA​:
- Carries each amino acid to ribosome (one specific tRNA for each amino acid)​
- Contains anticodon (3 bases) complementary to sequence of 3 bases (codon) on mRNA​
- Amino acid transferred to growing polypeptide chain​
- Sequence of mRNA codons determines sequence of amino acids in a protein​

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how many amino acids exist?

A

20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is a mutation?

A

a random permanent alteration in a DNA sequence
caused by:
- Errors in DNA synthesis that can occur spontaneously at low frequency​
- Chemical mutagens ​
- Ionising radiation​

17
Q

describe the different possible effects of a substitution mutation?

A
  • Conservative mutation: amino acid is replaced by one with similar properties​
  • Non-conservative mutation: amino acid is replaced by one with different properties​
  • No mutation: in many cases a change in the third position of the codon does not change an amino acid​
18
Q

what does insertion/deletion of a base?

A

Causes a frame-shift, and hence synthesis​
of a protein that has a completely different​
sequence downstream of the mutation:​
​
If any of these changes introduces or removes a stop codon → premature or delayed termination​

Sickle-cell anaemia is caused by a single-base substitution (GAG to GTG) in the β-chain of haemoglobin​. This replaces glutamic acid with valine, which is a non-conservative mutation​
​
More drastic mutations may also occur eg.​
deletion or duplication of longer stretches of​
DNA​

19
Q

what is recombinant DNA technology?

A

DNA from different organisms is “cut and pasted” together, producing recombinant DNA​

20
Q

why is recombinant DNA technology important?

A
  • Vaccine production​
  • Protein therapies:​
    • human insulin​
    • human growth hormone​
    • interferon​
  • Production of blood clotting factors to treat haemophilia​
  • Gene is cloned into a plasmid which is then introduced into a bacterial cell; bacteria produce the protein, which is then purified and used in patients​
    ​
21
Q

what is gene therapy?

A
  • Replace faulty (mutated) gene with a healthy one or add a new gene into the genome ​
  • Used to treat or prevent disease e.g. cancer, diabetes, heart disease, cystic fibrosis, haemophilia ​
22
Q

what is gene cloning?

A
  • Produces large numbers of copies of a particular piece of DNA​
  • Genes are usually cloned by isolating them using restriction enzymes, followed by gel electrophoresis and inserting them into a plasmid​
  • Plasmid is then introduced into a bacterium, and the bacterium allowed to grow to produce large numbers of cells and hence many copies of the gene​
  • The gene can then be re-isolated using the same restriction enzyme​
23
Q

what are restriction enzymes?

A
  • Cut double-stranded DNA at specific DNA sequences​
  • These sequences are typically 4 to 6 base pairs in length and “palindromic” ie. they read the same in both directions​
  • Most restriction enzymes make a staggered cut (“sticky ends”), which allow DNA fragments to re-associate by base pairing​
  • After re-association, the fragments can be rejoined by DNA ligase​
24
Q

describe gel electrophoresis

A
  • Used to separate DNA fragments on basis of their size​
  • Samples are applied to a gel immersed in buffer and a current is applied​
  • Negatively-charged DNA migrates from the negative electrode (top of gel) to the positive electrode (bottom of gel)​
  • Larger DNA fragments migrate more slowly than smaller DNA fragments​
25
Q

describe the procedure of gene cloning

A
  • To insert a gene into a plasmid, a restriction enzyme is chosen that cuts on either side of the gene but not in the middle​
  • The gene is separated from other DNA fragments by gel electrophoresis​
  • A suitable plasmid is linearised (cut at one point) using the same restriction enzyme​
  • The cut plasmid and gene are mixed, and the sticky ends of the plasmid and gene are allowed to “anneal” (associate by base pairing)​
  • The annealed ends are covalently joined using DNA ligase​
  • The plasmid, now containing the gene of interest, is introduced into the host bacterium​
  • The bacteria are grown into a colony, using antibiotic resistance genes in the plasmid to select colonies containing plasmids​
  • Cloned cells are lysed and the plasmids isolated by centrifugation​
  • Plasmids are cut with the restriction enzyme, releasing the cloned gene​
26
Q

what is Sanger sequencing?

A
  • Also known as the dideoxynucleotide chain termination method ​
  • Remains in wide use, generally for ​small-scale projects e.g. single genes​
  • Synthesis of new DNA strands complementary to a single-stranded template strand in vitro​
27
Q

what is a primer?

A

short strand of bases, serves as a primer for synthesis of the complementary DNA strand by primer extension

28
Q

what is the function of DNA polymerase?

A

enzyme that catalyses DNA strand synthesis

29
Q

describe chain termination

A
  • Interruption of DNA strand synthesis depends on presence of ddNTPs​
  • 3’ OH group of dNTPs replaced by H in corresponding ddNTP​
  • ddNTPs incorporated into growing DNA chain (as the final nucleotide) but lack 3’OH required to form a phosphodiester bond with next nucleotide → chain termination​
  • Synthesis is interrupted at every possible site in a given population of molecules, resulting in hundreds of DNA fragments of varying length​
  • ddNTPs are added at a much lower concentration than the standard dNTPs (ratio of 1:10 to 1:300) to allow strand elongation sufficient for sequence analysis​
30
Q

what is the procedure for DNA sequencing?

A
  • DNA to be sequenced is mixed with primer​
  • Primer binds to 3’ end of DNA​
  • DNA-primer mixture divided into four separate reaction tubes containing:​
    • all four dNTPs​
    • one of the four ddNTPs (A, C, G, T tubes)​
    • DNA polymerase​
  • Chain synthesis proceeds in each of the four reaction mixtures​
  • Gel electrophoresis separation of reaction products → band corresponding to each position of chain termination appears​
  • DNA bands detected by autoradiography (35S) or by laser in an automated sequencer (IRD800)​
  • DNA sequence can be deduced from the pattern of bands in the four lanes:​
    • a dark band in a lane indicates a DNA fragment that is the result of chain termination after incorporation of a ddNTP​
    • the terminal nucleotide base can be identified according to which ddNTP was added in the reaction giving that band​
    • the relative positions of the different bands among the four lanes are then used to read (from bottom to top) the DNA sequence.​
31
Q

what is high throughput sequencing?

A
  • Also known as next generation sequencing (NGS)​
  • No need for cloning, highly scalable​
  • Sequence millions of genes and entire genomes at once​
  • Cheap and rapid​
  • Requires substantial bioinformatics analysis​
  • Key platforms: Illumina (HiSeq, MiSeq), Roche 454, Ion Torrent (PGM, Proton)​

BDS1 BAMS molecules and cells (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions