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Bio 107 > Genetics, Cell Division, and Gene Expression > Flashcards

Genetics, Cell Division, and Gene Expression Flashcards

1
Q

What is a nucleotide made up of?

A

Pentose + Base + Phosphate(s)

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2
Q

How are carbons numbered in sugar in nucleotides?

A

The 1’ goes at the sugar connected to the carboxyl.

The Nitrogenous base is attached to the 1’ prime carbon

The Phosphate groups are attached to the 5’ carbon

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3
Q

What is a nucleoside?

A

Just the nitrogenous base and the sugar in a nucleotide

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4
Q

What are the purines

A

These nitrogenous bases have two rings
* Adenine (A)
* Guanine (G)

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5
Q

What are the Pyrimadines

A

These nitrogenous bases only have 1 ring
* Uracil (U)
* Cytonsine (C)
* Thymine (T)

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6
Q

“Reading” vs “Writing” directionality of DNA

A

3’ → 5’ (Reading)
5’→3’ (Writing)

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7
Q

How many H-bonds are there in an A-T bond?
How many in a C-G bond?

A

A-T: 2 H-bonds

C-G: 3 H-bonds

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8
Q

Is DNA symetrical on both sides?

A

DNA is twisted into a helix, but it is not symmetric

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9
Q

What do DAPI stains attach to in cells

A

The DAPI stain attaches to the minor groove of DNA
* It aslo stains organelle DNA (mitochondria and chloroplasts)

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10
Q

What are the different types of double stranded DNA?

A

A-DNA
Adaptation to desiccation?

B-DNA
Most common type by far

Z-DNA (left handed)
Implicated in disease?

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11
Q

Prokaryotic Chromosome

A

Circle of double-stranded DNA
* 0.5 – 7.0 Mb long
* Most bacteria have 1 copy per cell
* It contains all the genetic information needed to function and reproduce
* It is replicated during cell division

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12
Q

Prokaryotic Nucleoid

A

60% DNA (circular chromosome) + DNA-binding proteins not forming nucleosomes
* Arguably some RNA
* NO membrane!

This is the Prokaryotic equivilant of a chromosome

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13
Q

Prokaryotic Plasmids

A
  • Usually small (but it can be quite large)
  • Circular dsDNA
  • No DNA-binding proteins
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14
Q

What are the different ways of storing DNA (in order of most availible to least availible)

A
  1. DNA
  2. “beads on a string”
  3. 30 nm fibre
  4. 120 chromonema
  5. 300-700 nm chromatid
  6. 1400 nm mitotic chromosome (supercoiled lineral DNA)

Note: organelle DNA stays circular

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15
Q

What are the states of active DNA

A
  • DNA
  • Beads on a string
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16
Q

Single-Strand Binding proteins

A

SSB proteins prevent annealing (coming back together) of the separated strands and protects the open strand from enzymatic attack

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17
Q

The “Central Dogma”

A

Information flows from DNA (to DNA) to RNA to proteins

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18
Q

Where does DNA stay? Where do ribosomes stay?
How does the DNA get to ribosomes?

A

DNA is (and stays) in the nucleus

Ribosomes are (and stay) in the cytosol

Conclusion: RNA shuttles information from the DNA in the nucleus to the ribosomes in the cytosol where proteins are made

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19
Q

What is a gene?

A

A portion of DNA that encodes a functional RNA

Can be protein-coding or non-protein-coding

Chromosome 1 examples:
* Gap junction protein conexin 31
* Collagen alpha 1

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20
Q

Messenger RNA (mRNA)

A

Messenger RNA is responsible for relaying the information stored in DNA

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21
Q

How many Nucleic Acids do we make?

A

DNA: only 4 bases
Protein: 20 residues (+2)

3 Bases = 1 Codon → 1 Amino Acid

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22
Q

Mutations

A

Are changes in the sequence of bases in the DNA

Are sometimes visible, other times not

Can be deleterious, neutral, or beneficial

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23
Q

Variants

Genetics

A

When a change does not affect function but rather strength of a phenotype is often called a variant

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24
Q

What are the types of genetic mutations

A

Framshift
* Deletions (single base or codon)
* Insertions(single base or codon)

Base Substitutions

Note: Many of the base substitutions are invisible mutations

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25
Q

Semi-Conservative Replication

A

When DNA duplicates, it keeps one strand and makes a new one

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26
Q

DNA replication Summary (Bacterial Model)

A

Separation
● Straightening → Topoisomerase
● “Unzipping” → Helicase
● Maintaining strands separated → Single-strand-binding proteins

Elongation
● RNA Priming (sometimes DNA) → Primase (a kind of polymerase)
● Synthesis → DNA Polymerase III
● Proofreading → DNA Polymerase III
● Replacing RNA with DNA → DNA Polymerase I
● “Stitching” DNA → DNA Ligase

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27
Q

Replication Fork

Genetics

A

Topoisomerase relaxes the double helix so it can be “unzipped” without the tensions created by the twist

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28
Q

Class I Topoisomerase

A

Cuts the sugar-phosphate backbone to allow for over-/under- winding, then repairs the bond once it’s done

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29
Q

Helicase

A

Pulls apart the double strand so each strand can be accessed individually

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30
Q

Which direction do you transcribe the template strand?

DNA

A

3’ to 5’ (reading)

Note, the nucleotides you’re adding are from the 5’ to 3’ direction

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31
Q

What needs to happen before DNA pol III can add nucleotides to a lone template strand?

A

Primase needs to create a primer of ~10 RNA NTs on the DNA template strand

DNA pol III can add dNTPs once a primer is in place

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32
Q

What is the function of primase?

A

Primase is a kind of RNA polymerase It adds RNA nucleotides:
● ATP
● UTP
● CTP
● GTP
onto a template strand

This must be done before DNA polymerase can add nucleotides to the template strand

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33
Q

What are the functions of DNA (or RNA) polymerase

A

Many different types exist they all:
● Add nucleotides 1 at a time

Most of them also:
● Perform proofreading

Some of them also:
● Remove primers

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34
Q

What structure proofreads errors during elongation

A

DNA pol has a proofreading function, if the wrong base is added, it removes it before continuing, then adds the correct base and continues with the extension

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35
Q

Which direction is DNA elongated

A

5’ to 3’

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36
Q

Leading vs Lagging Strand

DNA Replication

A

Leading strand follows the direction of DNA helicase.

The lagging strand elongates in the opposite direction of the DNA helicase.

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37
Q

Whats an Okazaki fragment

A

The little bits of code on the lagging strand

Note: not the primer

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38
Q

What is the function of DNA Ligase

A

Ligase joins broken DNA

Useful for joining Okazaki fragments during replication but also for repairing DNA that has been damaged by environmental factors such as radiation

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39
Q

Explain DNA Replication in the Bacterial Chromosome

A

The circular bacterial chromosome has a single origin of replication

From the OOR, two helicases begin to separate the strands in opposite directions, forming a replication bubble

Eventually the replication forks meet and the replication is complete
* Termination sequences and a special protein help to seperate the forks where they meet

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40
Q

Explain DNA Replicaton in the Eukaryotic Chromosome

A

The linear eukaryotic chromosome has a multiple origins of replication

From each OOR, two helicases begin to separate the strands in opposite directions, forming a replication bubble for every origin

In humans there are about 100000 OOR in total

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41
Q

What’s a Telomere? What does it do?

A

Telomeres are repetitive sequences (TTAGGG mammals)

The ends of eukaryotic chromosomes are capped by telomeres

DNA pol cannot copy to the very end of a strand so capping sequences provide a buffer to avoid information loss

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42
Q

Telomerase

A

Telomerase maintains the telomeres

The activity of the enzyme is reduced in adult cells and one of the theories of aging involves the shortening of the telomeres leading to health problems as cells divide

Note: too much tlomerase activity is linked to cancer

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43
Q

Explain DNA replication in Achaea

A

Circular chromosome but multiple origins of replication

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44
Q

What nitrogenous bases ten to be rich in origins of replication

A

Origin of replication sequences tend to be AT-rich

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45
Q

Polymerase Chain Reaction (PCR)

A

A laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA

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46
Q

Explain the significance of thermophilous bacteria

A

Thermophilous bacteria revolutionized molecular biology

As a thermophile, its enzymes are stable at high temperatures

The DNA pol used in PCR comes from T. aquaticus and is known as Taq pol

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47
Q

Transcription

A

The synthesis of RNA from DNA

RNA becomes a messenger carrying DNA instructions

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48
Q

RNA polymerase

A

Does everything:
● Separates DNA
(no helicase needed)
● Reads DNA and synthesises RNA
● Proofreads the growing RNA strand

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49
Q

Which direction is “upstream”

A

Upstream - Toward the 5’ direction
Downstream - Toward the 3’ direction

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50
Q

Antisense strand

A

Another word for template strand

RNA pol only reads this

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51
Q

Promoter

Genetics

A

● A region used to recognise the “beginning” of a gene during transcription

● Transcription factors and RNA pol bind to different sections of the promoter to begin transcription

● TATA box is a conserved sequence of most promoters and marks the specific section for RNA pol to bind to

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52
Q

TATA Box

Genetics

A

● The general TATA sequence is TATAWAW (W can be A or T)

● TATA-box binding protein binds to the TATA box sequence and crimps the DNA

● RNA pol binds downstream of this protein to begin transcription

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53
Q

Initiation

Genetics

A

The process assembling all the machinery needed for transcription to occur

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54
Q

The 35s Promoter

A

A gene alone is not enough to make a protein, the promoter has the function of telling RNA pol to make RNA from the gene

Regularly used to drive the expression of recombinant proteins in plants

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55
Q

Intrinsic Termination

A

The same transcript that is being produced signals the termination of the transcription

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56
Q

Operon

Genetics

A

● The operon is a gene structure that allows more than one gene to be controlled by the same operator

● Example: lac operon, the genes that control proteins related to lactose acquisition and metabolism

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57
Q

Was the process of transcription like in bacteria

A

Transcription coupled to translation

● No further processing of RNA is required

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58
Q

Was the process of transcription like in Eukaryotes

A

The transcribed RNA needs further processing in Eukaryotes

● In eukaryotes, transcription produces immature messenger RNA or ‘pre-mRNA’

● pre-mRNA processing is known as
post-transcriptional modification

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59
Q

5’ Capping

A

A modified guanosine is added at the 5’ end: 7-methylguanosine

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60
Q

3’ end trim

A

● 10 – 30 nt downstream of the sequence AAUAAA (or AUUAAA) the end of the capped pre-mRNA is cleaved (cut off)
● Many factors are involved

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61
Q

Polyadenylation

A

● A long tail of adenosines is added at the 3’ end (about 250-nt long)

● This is known as polyadenylation

● Poly-(A)-polymerase adds the ATP’s

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62
Q

Splicing

Genetics

A

● Introns are removed

● Messenger RNA (mRNA) is now mature

63
Q

Major types of RNA

A

● mRNA — Messenger
● rRNA — Ribosomal
● tRNA — Transference

64
Q

Whats the steps of processing rRNA

A

This is highly efficient: transcribe a single gene, obtain three separate components

rRNA makes up the ribosomes together with proteins

65
Q

What are the steps in processing tRNA

A

tRNA is the RNA that transfers single amino acids to the ribosome during protein synthesis

Processing is necessary to force the tRNA into the proper shape to fit in the ribosome

66
Q

Why do we modify bases?

Genetics

A

Modified bases let tRNA assume complex shapes not achievable with regular bases

Common modifications:
* Adenosine (A) → Inosine (I)
* Uridine (U) →Pseudorine (♆)

67
Q

Tertiary Structure of tRNA

A

Complex 3D twists and turns give the tRNA a functional shape

68
Q

True or false

Prokaryotes process mRNA

A

False
* Only Eukaryotes do this

69
Q

Summarize mRNA processing

A

This is a multi-step process done to ensure the integrity of the mRNA
* This is also known as
* post-transcriptional
* modifications
* Fully-processed mRNA is also called mature mRNA

Steps:
* Capping
* Cleaving
* Polyadenylation
* Splicing

70
Q

Alternative Splicing

Genetics

A

“Cutting out” different bits of the same genetic code to make different protiens

71
Q

Translation

Genetics

A

The synthesis of protein from RNA (mRNA)

DNA: encrypted instructions

mRNA: unencrypted message

Protein: translated (effected) message
* Puts the intructions in the message into action

72
Q

How to amino acids get onto the tRNA

A

Amino acids need to be “loaded” onto tRNA

Aminoacyl-tRNA synthetase binds the tRNA (catalytic site) and attaches the amino acid at the 3’ end (editing site)

73
Q

Aminoacyl-tRNA synthetase

A

“Aminoacyl-tRNA synthetase” is any enzyme from a family of synthetases
* There is one for each tRNA-aa pair

Aminoacyl-tRNA synthetase binds the tRNA (catalytic site) and attaches the amino acid at the 3’ end (editing site)

74
Q

What needs to be done to amino acids befor loading them

Genetics

A

Before loading, aa’s need to be “activated”

aa + ATP → aa-AMP + PPi

aa-AMP + tRNA → aa-tRNA + AMP

75
Q

Wobble Pairing

Genetics

A

Some aa’s are encoded by multiple codons, but there is only one tRNA anticodon to match with each codon.

How? → The “wobble” position.

The “wobble” is made possible by modified bases

Inosine (I) can pair with C, U, and also A (recall than I is A modified)

Guanine (G) naturally pairs with U besides the normal C pairing

76
Q

Shine-Dalgarno Sequence

A

Prokaryotes contain a highly-conserved recognition sequence where the small ribosomal subunit binds:

AGGAGG[U]

There can be multiple of these sequences
* Transcripts with multiple Shine-Dalgarno sequences also have multiple START and STOP codons

77
Q

How does ricin (a poison work)

A

Ricin removes a single adenine from the sarcin/ricin loop in the ribosomal RNA, this inactivates the ribosome

78
Q

How does the death cap mushroom affect the body

A

It inibits RNA pol II

79
Q

Polypeptide = Protien?

A

NOPE

The polypeptide must be folded and have a purpose to be a protein

“Protein folding is the first, most obvious change that happens to a polypeptide chain after it has emerged from the ribosome”

80
Q

How important is protein folding?

A

The only thing that makes a protein work is its shape!!!

Wrong shape = useless or
harmful
* Prions
* Alzheimers

81
Q

Are prions infectious?

A

Prions: infectious disease-causing proteins

Prions force normal proteins into bad shapes

82
Q

Chaperones

Genetics

A

Chaperones help proteins fold

They are proteins that protect other proteins from their surroundings so they can fold without interacting with other elements that could cause them to misfold

83
Q

Hsp90

Genetics

A

Hsp90 maintains protein “health” for a number of specific proteins

Exactly what these protein does is not entirely clear but is helps to maintain proper folding during stress
* It works with ATP and Sba1, a co-chaperone protein

84
Q

What are some common ways of modifying protiens?

A

Most proteins require changes before being functional

Cleaving - Protein function
Phosphorylation - General Activation
Acetylation - Gene Expression
Methylation - Protein Function

85
Q

Cleaving

Protein Modification

A

Bits and pieces of the polypeptide may have to be cleaved for proper function

Example: pepsin and pepsinogen
* Pepsin is an enzyme that digests proteins
* Pepsinogen is the proenzyme and it is not active
* In low pH, pepsinogen cleaves itself and becomes pepsin

86
Q

Protein Sorting

A

Proteins need to be localized to their target site within the cell
* Proteins have recogniseable sequences or “signals” used in trafficking

Target: cytoplasm → Free ribosomes simply release it in the cytoplasm

Target: cell compartment or
export → Ribosomes localise to the ER where polypeptides can be processed in the (ER’s) lumen

87
Q

What is the signal recognition particle

Protein Sorting

A

The signal recognition particle is a ribonucleoprotein
* Note: this is on the protein sequence

88
Q

Can some orgenelles make some of their own proteins?

A

Yes

Mitochondria and chloroplasts have their own ribosomes to make some proteins from their own mRNA transcribed from their own circular DNA

Example: RuBisCO’s large
subunit is synthesized by
chloroplasts’ ribosomes.

89
Q

How are proteins localized to different places (in Eukaryotes)

A

Cytosol
No signal → free ribo. → no signal

Nucleus Mitochondria, Plastids, Peroxisomes
No signal → free ribo. → organelle signal

Export
ER signal → ribo. @ ER → no signal

Plasma membrane, Nuclear envelope, ER, Golgi, Lysosomes
ER signal → ribo. @ ER → organelle signal

90
Q

How are proteins localized in prokaryotes

A

Localization happens by recognition of protein signal sequences

91
Q

What is the product of gene expression for protien-coding genes

A

For protein-coding genes, the product of gene expression is the protein it encodes

Note: Expression needs to be highly regulated or else chaos ensues

92
Q

How do prokaryotes regulate gene expression?

A

Prokaryotes mostly regulate at the transcription level

How much mRNA is made dictates how much product is available

93
Q

How to Eukaryotes regulate gene expression

A

Eukaryotes regulate at every possible level and then some

Every step that can be used for regulation is used for regulation

Why?
* Many Eukaryotes are multicellular, so unregulated protein-synthesis creates problems

94
Q

How do Eukaryotes cue transcription?

A

Eukaryotes use an enhancer region

Together with specific transcription factors (activators) they are part of the transcription initiation complex

95
Q

All cells in your body have the same DNA. How come your skin cells and your liver cells show different genetic expression?

A

All cells share the same genes, but different genes are expressed in different cells

Multicellular Eukaryotes need to coordinate which cells express what

Together with specific transcription factors (activators) they are part of the transcription initiation complex

96
Q

How does miRNA regulate translation

A

miRNAs interrupt the translation process by binding to the mRNA and impeding the ribosome

97
Q

What influences the life of the transcriptome

A

5’ UTR’s imprint the half-life of the transcript

Poly-A tail length affects the half-life R

98
Q

Ubiquitin

A

● Regulatory protein used by most Eukaryotes
● It’s called ubiquitin because it’s ubiquitous!
● It’s a small protein, just 76 aa-long in humans

Ubiquitin proteins tag other proteins.
At least 4 needed for degradation

Affects protein:
● Degradation
● Location
● Activity
● Interaction

99
Q

Proteasome

A

Protein shredder

● Destroys proteins
● Active sites are on the inside to protect the cell
● The ends are capped
● Shreds proteins into 3 – 23 aa-long pieces

100
Q

True or False

Epigenetics are changes to the DNA code

A

Epigenetics are changes to the DNA molecule, but not to the code!
* Histone tails can be acetylated, DNA can be methylated
* DNA methylation is said to “tag” the DNA in specific ways

101
Q

Chromatin remodeling

A

Semipermanent and heritable.

Large implications such as in addiction models and other social issues such as trans-generational trauma.

102
Q

X chromosome inactivation

A

Some female mammals (including humans) randomly inactivate one copy of their X chromosome

Example: the coat pattern of a calico cat

103
Q

Do mutations need to occur in the protein-coding region to have an effect?

A

NOPE

Mutations need not occur in the protein-coding region to have an effect

Example: Haemophilia

Several possible mutations. Most common forms involve a mutation to the promoter of a gene coding for a clotting factor.

104
Q

Single-nucleotide polymorphism (SNP, pronounced ‘snip’)

A

A variant in the code of at least 1% of the population

Example: sickle-cell anemia
* Single-base substitution missense mutation in the 6th codon of the gene coding for haemoglobin
* Non-conservative
* mutation (aa’s with different properties)

105
Q

Can Sickle-Cell Anemia be Advantageous?

A

Yes

Sickle-cell: a recessive evolutionary advantage

~4 million are homozygous
~43 million are “sickle trait”

Heterozygous “sickle-trait” individuals have resistance to malaria
* 80% of cases occur in Sub-Saharan Africa

106
Q

Can silent mutations have an effect?

A

Yes

107
Q

True or False

All genetic disorders are mutations

A

False

Examples:
* Turner syndrome (missing X chromosome)
* Cri du chat (missing part of chromosome 5)
* Down syndrome (extra chromosome 21)

108
Q

What are some conditions started by SNPs

A
  • Sickle-Cell Anemia
  • Cystic Fibrosis
109
Q

Sumarize the prokaryotic cell cycle

A

● B period: cell growth
● C period: DNA
replication
● D period: fission

THIS IS NOT MITOSIS!!!!

This is also exponential growth (in theory)

110
Q

What is the name for Prokaryotic Cell Division

A

Binary Fission

111
Q

ParABS system

A

The ParABS system ensures that the chromosome is segregated, the full mechanism is under investigation

Proteins parA and parB move the chromosome, without polymerising into long chains
* Not cytoskelital involvement

Prokaryote Exclusive!

112
Q

What is parS, where is it Located?

ParABS system

A

ParS is a well conserved region of DNA
* It does not make a product, but s very useful in Prokaryotic DNA replication

It is located next to the origin of replication, making it the first to be replicated in DNA replication

113
Q

What does ParB bind to? What does it do from there?

ParABS system

A

It binds to ParS

parB proteins are guided to move toward the opposite pole guided by a concentration gradient of parA proteins

114
Q

How come both origins of replication don’t follow the ParA protien gradient?

A

ori #1 is anchored at the membrane at one of the cell’s poles
* This makes it so only ori # 2 can follow the gradient

ori #2 is anchored at the other pole once it gets there

115
Q

Endospore Formation

A

This is a process that only occurs for some bacteria
* Only occurs when environmental conditions get hard

● Fission starts but stops at cell expansion
● A double-membrane capsule is formed around one chromosome
● The rest of the cell dissolves
This forms an endospore that can wait it out until conditions improve

116
Q

What does the endospore structure constist of?

A

Includes:
● Double membrane
● One chromosome
● A few copies of DNA pol
● A few ribosomes

Excludes:
● Water (mostly)

117
Q

Summarize the Eukaryotic cell cycle

A

G1: growth and RNA synthesis, no DNA synthesis

S: Synthesis of DNA proteins and DNA replication

G2: further growth and synthesis of mitosis-related RNA and proteins

M: Mitosis

118
Q

Can cells exit the cell cycle?

A

Yes
* They can enter the G0 state, which stops them from starting DNA replication

Permanently: neurons
Temporarily: liver cells

In many tissues contact inhibition is a major trigger to enter the G0 state (cells can sense their neighbours)

119
Q

What are the different rates of cell division

A

Some cells reproduce continuously, e.g.:
● Epithelial cells replace themselves
● Bone marrow is highly active

Some cells reproduce if required, e.g.:
● White blood cells
● Hepatocytes (liver cells)

Some cells cannot / will not, reproduce, e.g.:
● Neurons
● Red blood cells

120
Q

What are the distinct phases of mitosis

A

Prophase: condensation

Prometaphase: spindle formation

Metaphase: chromosome alignment

Anaphase: separation of chromatids

Telophase: unpacking

121
Q

G1: growth

Cell division

A

Cell synthesises proteins and ribosomes, and reproduces organelles in preparation for cell division

Assembly and loading of cohesin proteins

122
Q

S: replication

A

DNA replication

Replication creates two chromatids from each chromosome

Cohesins are trimeric proteins that hold sister chromatids together

All of this happens in the nucleus

123
Q

Centrosomes

A

The centrosome (a pair of centrioles) is replicated during the S phase, along with DNA (but in the cytoplasm)

Animal Only!!

124
Q

G2: further growth and synthesis of all mitosis-related machinery

A

DNA is already duplicated, awaiting further cell preparations before division

Mitotic chromosomes are inaccessible, so all the components needed to carry out mitosis need to be synthesised before the DNA is fully condensed

125
Q

What do condensin protiens do?

A

Condensin proteins contribute to chromatid condensation
* Cable Managment
* Keeps the chromasomes condensed

126
Q

Karyotype

A

Diploid organisms have pair of homologous chromosomes
● Humans: 23 pairs
● Jack jumper ants:
○ Females: 1 pair
○ Males: 1 single (haploid)
● Ophioglossum pycnostichum:
630 pairs!!! ← a fern

127
Q

how are sister chromatids anchored at one point

A

Condensed sister chromatids remain attached at one point by the centromere

A complex of proteins bind to specific regions in each chromosome, holding both chromatids

Centromere placement varies in each chromosome

128
Q

Prometaphase

A

Spindle formation and nuclear dissolution

The spindle forms the tracks on which the chromosomes ride

Between prophase and metaphase, the spindle forms from the centrioles

It’s called a spindle for its shape, reminiscent of a drop spindle used for spinning yarn
What’s the spindle made of?

129
Q

What do kinetochore proteins do

A

Kinetochore proteins are attached to the centromere
* Attaches chormasomes to the microtubule of the spindle

They link the mitotic chromosomes to the spindle

130
Q

What happens during metaphase

A

Chormosome alignment

131
Q

What happens during anaphase

A

Seperation on chromatids and elongation of the cell

132
Q

How does cytokinesis work in animal cells

A

In animal cells, microfilaments divide the cell

They create a furrow by forming a ring around the equator and contracting it, like a drawstring

133
Q

Differences in mitosis in plant cells (as opposed to animal cells)

A

Difference #1:
Cells expand during interphase, never during anaphase
* Plant cell walls need to loosen up to allow expansion
* Plants need to deal with the very specific process of cell expansion before or after attempting mitosis (but not during)

Difference #2:
No centrosomes
* But they do still have a mitotic spindle!

Difference #3:
No furrow in cytokinesis
* A phragmoplast forms a scaffold and vesicles deposit new cell wall

134
Q

What are the major checkpoints of cell division

A

G1 — End of G1
Regulatory Protein: G1-CDK

G2 — Start of mitosis (G2/M)
Regulatory Protein: M-CDK

M — Start of anaphase
Regulatory Protein: APC

Regulatory proteins give the “go ahead” at each checkpoint

The cell cycle can be halted at any of these points

135
Q

G1 Checkpoint

A

Controls the entry into the
S phase

This is the “commit to
division” checkpoint

Unicellular: is the cell large enough to reproduce?

Multicellular: is the cell supposed to reproduce?
* Neuron?
* Too close to other cells?

If all checks out:
● Activate G1-CDK
Otherwise:
● Remain in G0

136
Q

G2 Checkpoint

A

Controls the entry into mitosis

Is DNA replication and repair
complete?
→ If no, wait
→ If yes, form the M-CDK complex (different cyclin and different CDK from G1)

M-CDK phosphorylates proteins involved with chromosome condensation

137
Q

M Checkpoint

A

**Controls entry into anaphase **

Is every chromosome
attached to kinetochore MTs? → If no, wait
→ If yes, activate APC proteins

APC: anaphase-promoting complex; signals other proteins to break down cohesins

138
Q

Mammalian growth factors

A

Growth factors regulate cyclin-CDK complexes

Can be:
● Positive (Platelet-Derived
Growth Factor)
* Promotes cell division

● Negative (Myostatin)
* Inhibits cell division

139
Q

Minssense Mutation

A

A single nucleotide base in a DNA sequence is swapped for another one, resulting in a different codon and, therefore, a different amino acid

140
Q

Nonsense Mutation

A

A mutation that changes an amino acid in a protein to a stop codon which ends synthesis of the protein at that location.

141
Q

What is the start codon

A

AUG

142
Q

What are the stop codons

Name all three

A

UAA
UAG
UGA

143
Q

How are chromosomes moved during anaphase?

A

Kinetochores (motor protiens) rachet along the the microtubules, dissassembleing them in the process

144
Q

How is cytokenisis different in plants from animals

A

No furrow in cytokinesis

A phragmoplast forms a scaffold and vesicles deposit new cell wall

145
Q

In the ribosome, where does the tRNA first get loaded? Where does it exit?

A

Loading - A site

Creating amino acid - P site

Exiting - E site

146
Q

What is the role of aminoacyl transferase in translation

A

It attaches the right amino acid onto the right RNA sequence

147
Q
A
148
Q

Which direction does DNA replicate

A

5’ to 3’

Note: this is the DNA be added or the “writting” direction

149
Q

What are the steps of processing mRNA?
Why does mRNA need to be processed?

A
  1. Capping
  2. Cleaving
  3. Polyadenylation
  4. Splicing

This is done to ensure the integrity of the mRNA
* make sure the enzymes don’t eat it

150
Q

True or false

Proteins mark important places on the pre-mRNA in all cells

A

False

This only happens in Eukaryotes
* They are things like splicing factors and cleavage factors

151
Q

What is the name of the DNA region where the Pol begins?

A

The promoter
* The TATA box provides the specific section for RNA pol to bind to

152
Q

What is the name of the DNA region where the Pol finishes

A

The terminator
* May be intrinsic (ex. terminating hairpin) or factor dependant (ex. Rho factor)

153
Q

Variant

Genetics

A

When a change does not affect function but rather strength of a phenotype is often called a variant

Bio 107 (5 decks)

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