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MCBG > Intro to DNA I > Flashcards

Intro to DNA I Flashcards

1
Q

How does DNA store genetic information

A

DNA stores biological information in sequences of four bases of nucleic acid — adenine (A), thymine (T), cytosine (C) and guanine (G) — which are strung along ribbons of sugar- phosphate molecules in the shape of

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2
Q

How can DNA replicate itself without making mistakes?

A

Exonuclease,
Replicative DNA polymerases possess 3′ → 5′ exonuclease activity to reduce the misincorporation of incorrect nucleotides by proofreading during replication.
If there is an error it removes the nucleotides until error then is fixed

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3
Q

What causes the Two Groove sizes in a double helix
What are their names

A

Uneven twists head to two sizes of grooves
Major Groove
Minor Groove

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4
Q

What is the use of the Grooves in a DNA double Helix

A

Grooves permit proteins to bind to DNA and control its function (eg transcription)

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5
Q

What is Purine

A

There are two main types of purine:
Adenine and Guanine. Both of these occur in both DNA and RNA.

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6
Q

What is Pyrimidines

A

There are three main types of pyrimidines, however only one of them exists in both DNA and RNA: Cytosine. The other two are Uracil, which is RNA-exclusive, and Thymine, which is DNA-exclusive.

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7
Q

What do Genes code for

A

Most genes code for proteins
Some code for molecules of RNA

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8
Q

Where are Genes located

A

Genes are located on chromosomes with a specific
“address”

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9
Q

How many Genes does a human have

A

Humans have around 25,000 genes

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10
Q

What is a Genome

A

the complete set of genes or genetic material present in a cell or organism.
(The genome contains the entire DNA sequence)

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11
Q

How many chromosomes does a person have

A

Each person has 46 chromosomes (2 x 22 autosomes) + X&Y or X&X

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12
Q

What does diploid mean

A

A diploid cell has two complete sets of chromosomes.

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13
Q

How many Genes are in the Y chromosome

A

Y chromosome is much smaller (70 – 200 genes)

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14
Q

How many genes in the X chromosome

A

X (is larger) chromosome 900 – 1600 genes

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15
Q

What is inside the X and Y Chromosome

A

-Contain pseudoautosomal regions (PAR)
and
-genes needed for sex determination,
similar on X and Y

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16
Q

What is SRY

A

(Sex-determining region on the Y protein)
- initiates male sex determination. Starts seminiferous tubule development.
- Needed to produce sperm in the Testis

17
Q

On Average how much DNA has to fit into a cell

A

On average about ~ 2 metres of DNA fits into a 6 µM cell

18
Q

What is HeteroChromatin

What is its appearance under an electron microscope?

A

-Heavily Condensed Chromosome
-Usually occurs when the activity of the genes is modified or suppressed.
-Appears Darker under an electron microscope

19
Q

What is Euchromatin

What is its appearance under an electron microscope?

A
  • Unwounded, Less condensed Chromosome
  • Often shows where genes are under active transcription
  • Lighter colour under an electron microscope
20
Q

What is DNA wound around

A

DNA is wound around histone proteins

21
Q

How do histones and DNA bind

A

Histones are made from different proteins called Octomers
These have a positive charge
This allows it to bind to the negatively charged DNA

22
Q

What is a histone core
How many base pairs does the histone core bind to

A

Histone core is an octamer
that binds about 147 bp (base pairs) of DNA

23
Q

What is a Solenoid

A

A solenoid is a secondary structure that compacts DNA into the nucleus

24
Q

What is the Diameter of the solenoid

A

30nm diameter

25
Q

When is DNA unwound

A

DNA has to be unwound to be copied during mitosis
(cell division)

26
Q

What is the structure of DNA and RNA

A

DNA and RNA are nucleic acids = polynucleotides,
(linear polymers of nucleotides)

27
Q

What is the difference between a nucleoside and a nucleotide?

A

Nucleosides contain only sugar and a base
Nucleotides contain sugar, a base and a phosphate group

28
Q

What is the difference between Ribonucleic Acid and Deoxyribonucleic acid

A

Ribonucleic Acid has a hydroxy group - RNA
Deoxyribonucleic acid has a hydrogen group - DNA

29
Q

What are the two types of Nitrogenous Bases and what is their structure

A

-Purine: Double Ring and has 9 members
-Pyrimidine: Single ring and has 6 members

30
Q

Example of a
Base, Nucleoside, and Nucleotide in RNA

A

RNA
BASE- Adenine
NUCLEOSIDE - Adenosine
NUCLEOTIDE - Adenosine Monophosphate (AMP)

31
Q

Example of a
Base, Nucleoside, and Nucleotide in DNA

A

DNA
BASE - Adenine
NUCLEOSIDE - Deoxyadenosine
NUCLEOTIDE - Deoxyadenosine monophosphate (dAMP)

32
Q

How are nucleotides joined together

A

Nucleotides are joined by phosphodiester bonds

33
Q

What are the district ends

A

The chain also has distinct ends: 5’ P and 3’ OH

MCBG (13 decks)

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