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Human Bio > Chapter 9 > Flashcards

Chapter 9 Flashcards

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Biology 101 flashcards
1
Q

What is a nucleosome

A

DNA strands wrapped around eight histone proteins

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2
Q

What is a chromatin

A

A tangled network of DNA in the nucleus of a cell that is not dividing

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3
Q

What is a gene

A

Section of a chromosome that contains the nucleotide sequence coding for a particular trait

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4
Q

What is the difference between nuclear DNA and mitochondrial DNA

A

Nuclear - long strands, bound to histones
mtDNA - small, circular molecules not bound to proteins

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5
Q

roughly how many molecules of mtDNA are found in each mitochondrion

A

5-10

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6
Q

What is a genome

A

The complete set of genetic information in an organism

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7
Q

How many genes are in mtDNA and what do they code for?

A

37 genes. 24 code for making transfer RNA. 13 code for making enzymes required for cellular respiration

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8
Q

How does helicase work

A

It breaks the weak hydrogen bond between base pair to separate the double helix

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9
Q

What is the role of DNA polymerase

A

Adds new nucleotides to the DNA strand

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10
Q

What is the role of DNA ligase

A

Joins short sections of DNA together

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11
Q

What is the role of messenger RNA

A

Takes genetic code into cytoplasm allowing genetic code to be read by ribosomes

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12
Q

What is the role of ribosomal RNA

A

Ensures correct alignment of mRNA and tRNA and ribosome. Has an enzymatic role in formation of peptide bonds between amino acids

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13
Q

What is the role of transfer RNA

A

carries a specific amino acid from the cytoplasm to the ribosome to add to a polypeptide chain

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14
Q

Summarize what transcription is

A

Process by which genetic information is copied from DNA to the mRNA

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15
Q

What triggers transcription

A

chemical messenger that enters the nucleus and binds to DNA at the relevant gene

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16
Q

What are introns and exons

A

introns - sections of DNA that DO NOT code for protein
exons - sections of DNA that code for protein

17
Q

What is the template strand and the coding strand

A

template - strand that is copied
coding - strand same as the one in the mRNA molecule

18
Q

What is the promotor region

A

section on the DNA where the mRNA can attach to initiate transcription

19
Q

Summarize translation

A

the production of a protein with the information provided by the mRNA

20
Q

What is the start codon

A

AUG, methionine, the point at which the ribosome first attaches to begin protein synthesis

21
Q

What is an anticodon

A

sequence 3 bases in tRNA molecule that binds to complementary codon in an mRNA molecule, to specify a particular amino acid

22
Q

How much energy does the formation of one peptide bond require

A

Breakdown of one ATP molecule

23
Q

What is gene expression

A

process of copying information from DNA on to mRNA and then translating the message into a series of amino acids to form a protein

24
Q

What does a gene being ‘switched on’ or ‘switched off’ mean

A

Genes that are making mRNA are switched on. Not making mRNA means they’re switched off

25
Q

What determines whether a gene is switched on or off

A

age of cell, environment, type of cell, time of day, signaling from other cells

26
Q

write the steps of protein synthesis (refer page 256)

A
27
Q

How are lipids and carbohydrates synthesized

A

by enzymes, which are proteins made from protein synthesis

28
Q

What is epigenetics

A

Altering expression of a gene without changing the gene structure. Can occur due to environmental factors

29
Q

What is acetylation

A

The addition of an acetyl group to a histone protein. Attraction between histones and DNA weakens, relaxing the chromatin structure. Promotes transcription by allowing polymerase access

30
Q

What is methylation

A

Addition of a methyl group to histone protein or DNA molecule. Occurs at sites where a cytosine is adjacent to guanine. Known as CpG sites, cytosine phosphorous–guanine. Inhibits gene expression by tightening molecule and restricting access to RNA polymerase. However, depending on where methyl group attaches and how many, it may increase or decrease transcription

31
Q

What is the difference between a gene and a chromosome

A

A gene is a segment of DNA that codes for making a protein and a chromosome is coiled up DNA

32
Q

describe the process of DNA replication (occurs during S phase) this is a semi-conservative process

A

Double helix un-winded by DNA helicase, weak hydrogen bonds broken between nucleotides. DNA polymerase works in 5’ to 3’ direction so nucleotides are assembled in continuous fashion on one end and short fragments on the other. These fragments are joined by DNA ligase. Each of the two new molecules with one OG strand and one new strand wind into a double helix

Human Bio (6 decks)

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