Lecture 5 DNA

Question 1

DNA is a macromolecule. What are the subunits (monomers) of DNA?

Answer 1

Nucleotides

Question 2

What is a nucleotide made of? (3)

Answer 2

1- A molecule of sugar
2- A phosphate group
3- A nitrogen containing molecule (base)

Question 3

What is the “backbone” of DNA made of?

Answer 3

Sugar + phosphate groups alternating

Question 4

What are the 4 possible bases of DNA?

Answer 4

Adenine, Thymine, Guanine and Cytosine

Question 5

What are the 2 possible pairs between the DNA bases?

Answer 5

A-T and G-C (or vice-versa)

Question 6

Why is the order of the nitrogen bases important?

Answer 6

Because it codes for the building of polypeptides (proteins)

Question 7

How is called the full set of DNA of an organism

Answer 7

Genome

Question 8

In what form is the DNA of procaryotes arranged? Where are they located?

Answer 8

circular, in the cytoplasm

Question 9

In what form is the DNA of eucaryotes arranged?Where are they located?

Answer 9

Linear, in the nucleus

Question 10

What are the separate pieces of DNA called?

Answer 10

Chromosomes

Question 11

What are called the 3000 bases long sequences of DNA?

Answer 11

Genes

Question 12

What is called the position of a gene on a chromosome?

Answer 12

Locus

Question 13

What is the use of genes?

Answer 13

Each genes codes for a specific protein

Question 14

How are called the different versions of a gene within a specie?

Answer 14

alleles

Question 15

When we talk about traits, we refer to…

Answer 15

The specific characteristics and features of an organism

Question 16

How much of our DNA is made of genes? What is the rest made of?

Answer 16

2% of our DNA is made of coding DNA (genes), the rest is “junk” DNA (non-coding)

Question 17

How are called the non-coding regions between genes?

Answer 17

Intergenic regions

Question 18

How are called the non-coding regions within genes?

Answer 18

Introns

Question 19

What are the 2 possible uses of non-coding gene regions?

Answer 19

Gene regulation or reservoir of potentially useful sequences

Question 20

What is a genotype?

Answer 20

All the genes that an organism carries for particular traits

Question 21

What is a phenotype?

Answer 21

The expression of a genotype (the particular traits)

Question 22

What are the 2 steps to go from a genotype into a phenotype?

Answer 22

Transcription and then translation

Question 23

What is the first step to DNA transcription? What happens?

Answer 23

Recognize and bind; RNA polymerase binds to the promoter site and splits the DNA into 2

Question 24

What is a promoter site? What does it do?

Answer 24

Its the base sequence that announces the start of a gene, that is where DNA polymerase will bind

Question 25

What is the second step of DNA transcription?

Answer 25

Transcribe: RNA polymerase builds a copy of the gene, which is called messenger RNA (mRNA)

Question 26

What are the 4 bases of mRNA?

Answer 26

A, U(uracil), C, G

Question 27

What are the pairs between DNA and mRNA bases?

Answer 27

T-A A-U G-C C-G

Question 28

What is the third step of DNA transcription?

Answer 28

Terminate; when polymerase sees the termination sequence of a gene, it stops copying it, and mRNA detaches from DNA

Question 29

In which cells mRNA needs more processing before moving onto other parts of the cell?

Answer 29

in Eukaryotic cells

Question 30

Where does mRNA goes after copying a gene?

Answer 30

From the nucleus to the cytoplasm

Question 31

Which molecule is involved in the translation part of DNA reading?

Answer 31

tRNA (transfer RNA)

Question 32

What does tRNA do?

Answer 32

It translates mRNA into amino acid chains

Question 33

How long is the sequence that indicates the formation of 1 amino acid on mRNA?

Answer 33

3 bases (= 1 codon)

Question 34

How many amino acids are there?

Answer 34

20

Question 35

What organelle is used to translate DNA into proteins?

Answer 35

Ribosomes

Question 36

What does the process of protein synthesis refers to?

Answer 36

The process where tRNA will read mRNA, and with the help of ribosomes, make amino acids and attach them into polypeptide chain

Question 37

What is gene expression?

Answer 37

the production of the protein that a gene sequence codes for

Question 38

What is gene regulation?

Answer 38

whether a gene is turned on or off

Question 39

What is a positive gene regulation?

Answer 39

Speeding up the production of proteins

Question 40

What is a negative gene regulation?

Answer 40

Slowing down the production of proteins

Question 41

What is Lac Operon? in which bacteria is it present?

Answer 41

It's present in E-Coli bacteria, and its a mechanism switched on when glucose is not present to nourish the bacteria; it will start to digest lactose for energy rather than glucose

Question 42

What is an operon in Lac Operon?

Answer 42

Its a system that controls gene expression of several genes as a unit, allowing the bacteria to switch its digestion to digesting lactose

Question 43

What is an enhancer sequence?

Answer 43

a nucleotide sequence that increases the rate of gene transcription

Question 44

How is negative control achieved?

Answer 44

When chemicals bind to DNA and block gene transcription temporairly

Question 45

What is a mutation in a gene sequence?

Answer 45

It is the alteration of the bases sequence in DNA

Question 46

What happens when mutations occur in the gametes?

Answer 46

The disease is transmitted to offspring

Question 47

What do most mutations do?

Answer 47

Nothing, most of them are on non-coding DNA

Question 48

What happens if a mutation occurs on coding DNA?

Answer 48

It can causes diseases and alter the production of proteins

Question 49

What is a point mutation?

Answer 49

When base pairs are substituted, added or deleted

Question 50

What is a chromosomal abberation?

Answer 50

When the organization of genes on a chromosome changes (it can be deleted = deletion, moved = relocation, or copied = duplication)

Question 51

What are the 3 chief causes of mutations?

Answer 51

1. Spontaneous 2. Radiation-induced 3. Chemically induced

Question 52

What is the path *briefly* from mutation to illness?

Answer 52

1. Mutated gene codes for non-functioning protein 2. enzyme (protein) does not catalyze reactions 3. the molecule it would have reacted with accumulates in the body 4. the chemical accumulation causes disease

Question 53

What is a possible tratment for mutations?

Answer 53

A medication containing the enzyme that the genes cant produce