Genome organisation and replication

Question 1

What are the essential macromolecules in the continuity of life?

Answer 1

Nucleic acids

Question 2

What does DNA stand for?

Answer 2

Deoxyribonucleic acid

Question 3

What is the role of DNA in a cell?

Answer 3

Carries the genetic inheritance and instructions for the functioning of the cell

Question 4

What does RNA stand for?

Answer 4

Ribonucleic acid

Question 5

What is the role of RNA in a cell?

Answer 5

Communicates genetic information to the rest of the cell

Question 6

What are the monomers that compose nucleic acids?

Answer 6

Nucleotides

Question 7

What are the components of a nucleotide?

Answer 7

Nitrogen base + sugar phosphate backbone

Question 8

What nucleotides compose DNA?

Answer 8

• Deoxyguanosine monophosphate (G)
• Deoxyadenosine monophosphate (A)
• Deoxythymidine monophosphate (T)
• Deoxycytidine monophosphate (C)

Question 9

True or False: RNA is responsible for carrying genetic inheritance in a cell.

Answer 9

False

Question 10

What are purines?

Answer 10

Two-carbon nitrogen ring bases

Question 11

What are pyrimidines?

Answer 11

One-carbon nitrogen ring bases

Question 12

Which bases are classified as purines?

Answer 12

Adenine and guanine

Question 13

Which bases are classified as pyrimidines?

Answer 13

Cytosine and thymine

Question 14

What are polynucleotide chains composed of?

Answer 14

Nitrogenous bases linked to a sugar-phosphate backbone

Question 15

How are nucleotides linked in a DNA strand?

Answer 15

By phosphodiester bonds (C-O-P-O)

Question 16

What gives the polarity of a DNA strand?

Answer 16

Phosphodiester bonds

Question 17

What is the structure that the sequence of nucleotides is organized into?

Answer 17

Antiparallel double-helix

Question 18

What two factors contribute to the stability of DNA double helix?

Answer 18

Hydrogen bonds between the bases of the opposite strands and base stacking of bases within a strand

Question 19

What proteins pack DNA into tight shapes?

Answer 19

histones

Question 20

What shape does packed DNA form?

Answer 20

chromatin

Question 21

what is a nucleosome?

Answer 21

complexes of DNA and 8 histones

Question 22

What are thr two types of chromatin conformation?

Answer 22

• open (euchromatin)
• closed (heterochromatin)

Question 23

Why is chromatin remodelling important?

Answer 23

allows DNA to be exposed in the open conformation and accessed for replication, transcription and repair

Question 24

what factors affect chromatin remodelling?

Answer 24

• Histone variants
• Histone post-translational modification
• ATP-dependent chromatin remodelling complexes.

Question 25

How does semi-conservative replication work?

Answer 25

DNA replication accomplished by separation of the strands of a parental duplex, each strand then acting as a template for synthesis of a complementary strand. The sequences of the daughter strands are determined by complementary base pairing with the separated parental strands.

Question 26

in what direction does replication take place?

Answer 26

5' to 3'

Question 27

which proteins seperate DNA strands for access of DNA helicase?

Answer 27

initiator proteins

Question 28

what does DNA helicase do?

Answer 28

breaks hydrogen bonds

Question 29

what does primase do?

Question 30

what does Topoisomerase do?

Answer 30

unwinds the DNA molecule

Question 31

what does dNTP loose when it joins the DNA strand?

Answer 31

two phosphate groups as a molecule of pyrophosphate

Question 32

what is the continuous strand in DNA synthesis called?

Answer 32

the leading strand

Question 33

what is the discontinuous strand in DNA synthesis called?

Answer 33

the lagging strand

Question 34

Why does DNA polymerase create problems for the linear DNA of eukaryotic chromosomes?

Answer 34

The replication machinery cannot complete the 5′ ends, leading to shorter and uneven DNA molecules after repeated replication.

Question 35

Why is the limitation of no 5' ends not a problem for prokaryotes?

Answer 35

Most prokaryotes have circular chromosomes, which do not have end-replication issues.

Question 36

What are telomeres in eukaryotic chromosomal DNA?

Answer 36

telomeres are special nucleotide sequences at the ends of DNA molecules

Question 37

What is the function of telomeres?

Answer 37

They do not prevent DNA shortening but postpone the erosion of genes near DNA ends

Question 38

What is a mutation?

Answer 38

A mutation is an inherited alteration in the DNA sequence, which can be inherited within the same organism and across generations.

Question 39

What causes mutations?

Answer 39

Mutations can be caused by replication errors or chemical damage to DNA

Question 40

How does the cell address mutations?

Answer 40

DNA repair mechanisms exist to correct mutations.

Question 41

what are the different types of DNA repair mechanisms?

Answer 41

- Base Excision Repair (BER) (Removes a single damaged base and replaces it) - Nucleotide Excision Repair (NER) (Removes bulky lesions) - Mismatch Repair (MMR) (Corrects errors made during DNA replication, such as mismatched bases or small insertions/deletions) - Homologous Recombination (HR) (Repairs double-strand breaks (DSBs) using a homologous template (usually the sister chromatid). - Non-Homologous End Joining (NHEJ) (Repairs double-strand breaks without a homologous template)