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Human Biology ATAR > Dna, Genes and Chromosomes > Flashcards

Dna, Genes and Chromosomes Flashcards

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1
Q

DNA stands for what and is found where?

A

Deoxyribonucleic acid
It is usually found in the nucleus of each cell (nuclear DNA), though some can be found in the mitochondria (mtDNA)

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2
Q

What does DNA contain?

A

It contains genetic information dtermining the structure of the cell and the way it functions.

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3
Q

What does RNA stand for?

A

Ribonucleic Acid

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4
Q

What are the two main types of the nucleic acids?

A

Dna and RNA

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5
Q

DNA is a polymer, what does that mean?

A

It means it is a molecule that is made up of many repeating small units

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6
Q

What are the repeating units in DNA?

A

Nucleotides

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7
Q

Does does each nucleotide consist of?

A

A sugar molecule (deoxyribose in DNA)
A phosphate group
Nitrogenous Base

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8
Q

What are the four nitrogen bases in the DNA molecule?

A

Adenine
Thymine
Cytosine
Guanine

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9
Q

What are the pairing of the nitrogenous bases and how are they attracted to one another?

A

Pyrimidines:
Cytosine - Guanine
Purines:
Adenine - Thymine
They are attracted to one another by weak hydrogen bonds

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10
Q

How is the genetic code of DNA determined?

A

By the order of the nitrogenous bases occurring.

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11
Q

How many DNA molecules does a human cell’s nuclei have?

A

46

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12
Q

Describe the ladder model

A

Example:
The ladder model consists of an untwisted double helix (displayed the molecule like a ladder)
The sides of the ladder (backbone) are alternating PHOSPHATE and SUGAR molecules.
The rungs are paired NITROGEN BASE molecules held together by a HYDROGEN bond

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13
Q

What are histones?

A

They are proteins that provide structural support for a chromosome.
Consists of a group of eight special proteins in which DNA strands are wrapped around.

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14
Q

What are chromatin?

A

The coiled DNA when it forms a tangled network in a cell that’s not dividing.

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15
Q

When is the DNA called chromosomes?

A

When the cell divides causing the coiled chromatin to become even more tightly coiled.

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16
Q

What is a gene?

A

It is the sections of DNA of each chromosome that code for a particular protein.

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17
Q

Where does the areobic phase of respiration occur?

A

The mitochondria

18
Q

What is the small amount of the cell’s DNA found in the mitochondria called?

A

Mitochondrial DNA or mtDNA

19
Q

From what is mtDNA only passed to?

A

From mother to child

20
Q

What are the differences between DNA and mtDNA?

A

Nuclear DNA is in the form of long strands bound to proteins, the histones.
Mitochondrial DNA is in the form of small circular molecules that are not bound to proteins.

21
Q

How many molecules are there in each mitochondrion?

A

5 - 10

22
Q

What are exons?

A

They are sections of coding DNA

23
Q

What are introns?

A

They are the sections of non-coding DNA
- They are used for turning on and off stuff, as well as the beginning of things.

24
Q

Through what processes does the divison of cells occur?

A

Mitosis
Meiosis

25
Q

What is it that DNa must produce for DNA replication?

A

It must produce an exact copy of itself.

26
Q

Leading strand in DNA replication:

A

Synthesised as a single polymer in the 5’ to 3’ direction

27
Q

Lagging strand in DNA replication:

A

Synthesised in the 5’ to 3’ direction, but discontinuously against the overall direction of replication.
There are gaps between what is being written.

28
Q

What are Okazaki fragment?

A

They are a series of short segments on the lagging strand.

29
Q

What enxyme separates the two strands of DNA replication?

A

Helicase

30
Q

Why is the helicase separation possible?

A

Due to the hydrogen bond between the base pairs being weak.

31
Q

How is the separated strang stabilised?

A

Single-stranded binding proteins (SSB) which attaches and helps to keep the separated strands apart.

32
Q

What does primase do?

A

It is a special RNA polymerase that synthesised an RNA chain that provides the priming end.

33
Q

Which two enzymes play important roles in the synthesis of the strands and how?

A

DNA POLYMERASE - adds the new nucleotides to the new strand
DNA LIGASE - joins short sections of DNA together.

34
Q

What are replication forks?

A

Hundreds of Y-shaped regions of replicating DNA molecules where new strands are growing.

35
Q

What are replication bubbles?

A

Hundreds of replicating bubbles happen due to the fact that DNA doesn’t just unzip seeminglessly, but every so often (kinda like the lagging strand)

36
Q

What is gyrase?

A

It is an enzyme that relieves stress on the DNA molecules by allowing free rotation around a single strand.

37
Q

What are RNA primers?

A

Before new DNA strands can form, there must be small pre-existing primers present to start the addition of new nucleotides (by DNA Polymerase III (can be described as the typewriter)).

38
Q

What is primase?

A

It is an enzyme that polymerises (synthesises) the RNA Primer

39
Q

What is DNA Ligase?

A

A linking enzyme that catalyses the formation of a covalent bond from the 3’ to 5’ end of joining strands.

40
Q

What is the difference between DNA polymerase iii and DNA polymerase i?

A

DNA polymerase iii - Main DNA builder
DNA polymerase i - Editing, repair & primer removal (comes back to check everything).

41
Q

Further Detail on DNA polymerase 1

A

Proofreads & corrects typos
Repairs mismatched bases
Removes abnormal bases
Repairs damage through life
Reduces error rate from 1 in 10,000 to 1 in 100 million bases

42
Q

What is protein synthesis

A

The process by which cells make new proteins

Human Biology ATAR (25 decks)

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