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Biology > Chapter 13 > Flashcards

Chapter 13 Flashcards

1
Q

What does RNA do

A

It transmits genetic information and makes proteins such as antibodies, channels, and enzymes

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2
Q

What is RNA

A

A nucleic acid with ribose sugar

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3
Q

How is RNA physically different from DNA

A

RNA is single stranded and uses Uracil instead of Thymine. And has ribose sugar

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4
Q

What are the three types of RNA

A

mRNA (messenger RNA)
rRNA (ribosomal RNA)
tRNA (transfer RNA)
The shape of the RNA determines its function

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5
Q

Where and how is mRNA made

A

Made in the nucleus by transcription. Is long, skinny, and straight. never folded

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6
Q

What does mRNA do

A

Carries the the DNA code (which is the instructions for amino acid assembly) to the ribosome to be made into a polypeptide chain (raw protein)

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7
Q

How many nucleotides are in a codon and what form of RNA are they in

A

3

And codons are Only in mRNA

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8
Q

What does rRNA do

A

Wraps around proteins (histo proteins) in the cytoplasm to form the two subunits that make up a ribosome
(Ribbon shape)

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9
Q

What is tRNA

A

Strand is folded to have two explicit ends. One end has the amino acid
The other end has three nucleotides (called an anticodon)
(Folded shape)

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10
Q

What is an anticodon

A

Only in tRNA. Made up of 3 nucleotides and it is specific to the amino acid it grabs. Is also complementary to the codon it will attach to (that’s why it’s anti-)

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11
Q

RNA synthesis = ?

A

Transcription

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12
Q

What is transcription

A

Segments of DNA (genes) are used as a template to create mRNA. Only copies one gene
(Not copying whole strand of DNA)

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13
Q

Step 1 of transcription

A

RNA polymerase breaks the DNA hydrogen bonds so the DNA uncoils and opens (the polymerase is specific to nucleic acid)

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14
Q

Step 2 of transcription

A

RNA polymerase binds to the DNA at a promoter site which is/marks the beginning of a gene

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15
Q

Step 3 of transcription

A

RNA polymerase brings in complementary nucleotides, building the mRNA, and proofreads

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16
Q

Step 4 of transcription

A

The DNA is read from 3’ to 5’ (rna is one strand so it is all the “leading strand”), so the mRNA is being built on its 3’ end. There are no Okasaki Fragments or terms of leading/ lagging

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17
Q

Step 5 of transcription

A

There is also a special end or stop signal/code/codon on the DNA to stop transcription and release the mRNA

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18
Q

Where does transcription take place in eukaryotes and prokaryotes

A

In eukaryotes it takes place in the nucleus

In prokaryotes it takes place in the cytoplasm

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19
Q

What is pre mRNA

A

Pre- mRNA will have parts of the gene that is needs and doesn’t need to make the proteins. It takes out from the code what it needs (these sections are called exons)
And leaves what it doesn’t (introns)
The exons will make up mRNA

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20
Q

After mRNA is made where does it go

A

Out of the nucleus

Exons exit nucleus, introns stay in nucleus (mostly)

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21
Q

Why r introns sometimes left in mRNA

A

To create different variations of a protein (recording show with or with out certain commercials analogy)

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22
Q

What is a polypeptide

A

A long chain of amino acids. The sequence determines the shape and function of the protein

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23
Q

A codon wheel or table ONLY refers to which RNA

A

mRNA (the 3 nucleotides/ codon is what is decoded on the codon wheel/table

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24
Q

How does tRNA and mRNA work together

A

The tRNA brings the proper amino acid to the mRNA strand by translating the genetic code on the mRNA

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25
Q

What is the genetic code

Universal code

A

It is the order of three bases/nucleotides at a time on the mRNA. Each 3 is a codon which is made up of a combination of A, U, C, G.
3 nucleotides=1 codon = 1 amino acid

(Is the series of codons)

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26
Q

What is the ONLY start codon

A

the ONLY start codon is AUG which translates to methionine.

There is only one bc you don’t want to confuse the system

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27
Q

Stop codons

A

There are multiple stop codons. They stop the polypeptide because there is no anticodon for a stop codon

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28
Q

What is a wobble

A

Synonymous codons-
Bc Some amino acids have more then one codon that can code for it . They are “synonyms” of each other.
Ex: CAC and CAU both code for Histidine

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29
Q

What is translation

A

The decoding of an mRNA message into a protein. Happens AT ribosome.
mRNA -> tRNA -> amino acid ->
Polypeptide/ protein

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30
Q

How does translation start

A

rRNA’s hold proteins in place and locate the beginning of mRNA using chemical attraction (senses cap of the AUG/methionine) so the rRNA will help mRNA get oriented and started in the right direction.

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31
Q

Step one of translation

A

mRNA attaches to ribosome (cap end) and start codon start codon AUG is read as methionine

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32
Q

Step two of translation

A

tRNA brings methionine to mRNA. the next tRNA with the 2nd amino acid sits on the mRNA next to methionine. And the previous amino acid (methionine) is peptide bonded to this 2nd amino acid. During this it detaches from its tRNA

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33
Q

Step three of translation

Elongation

A

The 1st tRNA leaves the mRNA as the 3rd tRNA with its amino acid sit down next to the 2nd amino acid. The 2nd amino acid detaches from its tRNA and peptide bonds to the third amino acid with the first still attached. This is called elongation and repeats until step 3.5

34
Q

Step 3.5 of translation

A

Step 3 repeats until a stop codon on the mRNA is reached. Since there is no anticodon/ amino acid for a stop codon the elongation stops

35
Q

Def. of elongation

A

The lengthening of the polypeptide chain by adding on amino acids

36
Q

Step four of translation

Last real step of translation

A

The stop codon attracts a protein releasing factor (instead of tRNA) and it takes everything apart, so the polypeptide falls of and immediately coils
tRNA let go, mRNA let go, ribosomes break apart back into 2 subunits

37
Q

Step 5 of translation

End translation start of ribosome building

A

The new polypeptide may now travel through the ER (endoplasmic reticulum) and/or the GA (golgi apparatus) for post translational modification
(starts back at step 1 of building proteins in ch 7.2 pg 200)

38
Q

What is the central dogma

A

In molecular biology it is the information that is passed from DNA to RNA in proteins
Info to run an organisms body.
Starts at DNA, goes to RNA. The pathway is called central dogma

39
Q

What is Gene expression

A

Refers to how the action of the proteins creates the characteristics show by the organism
(Gene made or not made)

40
Q

What are mutations

A

Changes in the genetic info, code, or sequence of nucleotides in the DNA
that (most) can be passed from generation to generation as the genes on the chromosomes are inherited
(Can be good, bad, neutral, or deadly)

41
Q

What are somatic changes

A

Mutations that are not/can not be inherited or passed down to other generations

42
Q

What are germ line mutations

A

Mutations that can be inherited

43
Q

What are point mutations

A

Mutations that occur or start at a single nucleotide (you can “point” to the start) in the DNA
(3 types)

44
Q

Point mutation 1: Substitution

A

Changes only one nucleotide. So it may or may not change only one amino acid

45
Q

What are frameshift point mutations

A

Changes the grouping of the nucleotide threesomes. The “reading frame” is shifted. Most cause dramatic, damaging, and/or deadly changes. From the one change on, the amino acids will be different. So the protein will not function normally or at all. (2 types)

46
Q

Point mutation 2:

Frameshift insertion

A

Adds one nucleotide into mRNA so that the threesomes are all shifted down/foreword one base and changed. Creating all new codons to be read.

47
Q

Point mutation 3:

Frameshift deletion

A

One nucleotide is subtracted or taken out so that all the threesomes following it are shifted back one base. Creating all new codons to be read

48
Q

What are chromosome mutations

A

Involve changes in the whole number or structure of a chromosome. Can change the location of genes or even the number of copies of genes
All may or may not affect organism
(4 types)

49
Q

What are the 4 types of chromosomal mutations

A

Deletion
Duplication
Inversion
Translocation

50
Q

Chromosomal mutation 1: deletion

A

A whole or part of a chromosome “drops out” or is loss

(Part of =gene)

ABCDEF
ACDEF

51
Q

Chromosomal mutation 2:

Duplication

A

All or part of a chromosome is repeated, creating an extra copy

(Part of = gene)

ABCDEF
ABBCDEF

52
Q

Chromosomal mutation 3:

Inversion

A

Reverses the direction of parts of the chromosome
Genes switch order when chromosome breaks and reattaches

ABCDEF
ACBDEF

53
Q

Chromosomal mutation 4: translocation

A 
Occurs when one chromosome breaks off and attaches to another. Genes move to other chromosomes when chromosomes break and the bits reattach to other different ones 
Only for non homologous chromosomes 
(NOT Crossing over)
GH ->
ABCDEF
ABGHCDEF
54
Q

What are mutagens

A

Chemical (pesticides) or physical (sunlight/X-rays) agents in the environment that cause changes in DNA

55
Q

What causes mutations most of the time

A

Mutagens

56
Q

What is polyploid

A

When all chromosomes go to one side
Can occur naturally but mostly breed.
Happens mostly only in plants
Is good bc it produces bigger, healthier, strong crops

57
Q

When is a gene expressed

A

Only when gene is transcribed, made into protein, and protein takes on its function

58
Q

What is a operon

A

A group of genes that function together. Their proteins act in concert to achieve a goal

59
Q

Gene regulation takes place where in prokaryotes?

A

Cytoplasm

60
Q

What is a repressor gene

A

Creates repressor molecules that will be present in the cytoplasm at all times. Is not needed, the repressor is sitting on its “spot” (operator) next to the promoter

61
Q

Where is repressor gene located

A

On the operator.

Located all the way to the left and is not part of the operon but will create operon molecule

62
Q

What is the promoter

A

Landing spot for mRNA polymerase.

Located between repressor gene and operator

63
Q

What happened when the repressor is moved

A

The RNA polymerase can bind to the promoter and transcribes genes

64
Q

How is the repressor moved using lac example

A

Lactose molecules change the shape of repressor so it falls of and moves
Takes only 1 or 2 lactose molecules (out of 1000’s) to trigger the repressor so that it can make lax genes to eat the rest

65
Q

Where does gene regulation in eukaryotes take place

A

Nucleus

66
Q

What is the TATA box site

A

It is next to the promoter and it marks the start of a gene. Marks where mRNA polymerase wants to sit

67
Q

What is the enhancer

A

It is before the TATA box and is the binding site (/landing spot) for transcription factors, to enhance the ability of RNA polymerase to bind to the promoter region.

68
Q

What are transcription factors

A

Made by the cell to be present in the nucleoplasm. Form a binding site for RNA polymerase. They will bind and release in response to chemical signals (ex: condition of molecules)
Also open up DNA and make DNA flexible

69
Q

Does every gene have its own enhancer and TATA box

A

Yes

70
Q

What is cell differentiation caused by?

A

Gene expression at various times in development

71
Q

Why do cells take on special shapes

A

For specialized jobs

72
Q

What are homeotic genes

A

Master control genes

Regulates organs that develop in specific parts of the body

73
Q

What are homeobox genes

A

Make transcription factors to turn genes on and off

74
Q

What are hox genes

A

Control body plans
Are arranged in the exact order they are expressed
Their function and arrangement is the same in almost all organisms. This is bc almost all animals share the same basic tools for building the different parts of the body
Later become species specific genes and hox die out (before birth?)

75
Q

Species specific genes

A

Control what specifically the basic body tools will turn into
Ex: arm bud from hox can turn into arms or wings or fins based on species specific genes.
The arms can then have fingers or paws or hoofs based on more species specific genes

76
Q

What do all embryos have in common

A

All embryos share same hox genes

77
Q

What do transcription factors do

A

Turn on and off gene products (in charge of gene expression)

78
Q

What happens to the rest of DNA while one gene is transcribed

A

It remains in touched

79
Q

Does the environment influence gene expression

A

Yes. In some animals it strongly influences the expression of a gene.
If temp is up then the maturation of frogs in the area speeds up

80
Q

What is the enzyme that binds to DNA during transcription

A

RNA polymerase

81
Q

How are the 3 RNAs different

A

mRNA- carries info from DNA to other parts of cell
rRNA- forms an important part of both subunits of the ribosome
tRNA- carries amino acid to the ribosome and matches them to coded mRNA

Biology (16 decks)

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