Chapter 17

Question 1

Chapter 17

Topics:

Answer 1

Transcription

Cell Specialization

Translation

Mutations

Question 2

Why RNA is necessary

Answer 2

DNA carries the genetic information for proteins, but only found in nucleus (eukaryotes)

Proteins are synthesized on Ribosomes

Requires an intermediate in RNA

RNA transfers genetic information from nucleus (DNA) to ribosomes in cytoplasm (location of protein synthesis)

Question 3

Transcription

Answer 3

Transcription is the process where RNA is synthesized from a DNA template

RNA is complementary to the DNA, except T is replaced with U

Question 4

What are some differences between DNA and RNA

Answer 4

RNA ONE SIDE IS SINGLE HELIX

Question 5

Transcriptions mechanisms

Answer 5

RNA molecules are synthesized by RNA polymerase

Adds bases in 3’ direction of

Pairings:
A U
T A
C G

Template strand (DNA) sets the bases, RNA transcript is the same as non-template DNA but U’s replace T’s

Question 6

Stages of Transcription

Answer 6

Initiation - RNA polymerase and support proteins binds to DNA and separate helix for transcription to start

Elongation- Nucleotides are added to 3’ end as RNA polymerase proceeds

Termination - RNA polymerase reaches a sequence that signals the end, and the RNA transcript is released

Question 7

Promoters

Answer 7

Sequences of DNA where RNA polymerase attaches

Includes TATA sequence, called TATA box initiation take solace 25 nucleotides downstream

Question 8

Terminators

Answer 8

Transcriptions stops at the terminator

RNA transcript is released

Question 9

Transcriptions regularity

Answer 9

One gene is transcribed by one strand, but one strand can transcribe many genes

Transcription is a regulated process, depending on need for product is can be continual or on an as-needed basis

Housekeeping gene Regularly go through transcription process

Inducible gene - transcription takes placed on an as needed basis

Question 10

RNA processing

Answer 10

RNA that carries off the template strand is known as the primary transcript

For protein coding genes it now has the information (from DNA to direct the ribosome to synthesize the corresponding protein)

Transcript goes through RNA processing to convert it self to finish mRNA

RNA molecule that directs synthesis within ribosome is mRNA

Question 11

Transcriptional Regulation

Answer 11

Requires use of transcription factors promotes, RNA polymerase

Cans stimulate or sedate transcription

Promoter- Sequence of DNA that proteins bind to initiate transcription

Question 12

Gene Regulation

Answer 12

When a gene is transcribed and translated to produce a functional proteins=Expressed

When a gene is not transcribed and translated = Not expressed

Amoeba Sisters Gene Regulation

Question 13

Gene Regulation Impact

Answer 13

Process by which genes are turned on and off

Gene regulation in eukaryotes leads to cell specialization

Major cell types look and function differently despite sharing the same genes due to
specialized cells

Question 14

What is translation? Why?

Answer 14

Process by which a molecule of mRNA guides the synthesis of a protein

Proteins are the functional macromolecule - they get things done

Regulatory Proteins - 1

Transport Proteins - 2

Structural Proteins - 3

Enzymes - 4

Question 15

Ribosomes

Answer 15

Site of protein synthesis

Made up of ribosomal RNA (rRNA) and protein

Found in plant, animal, and prokaryotes

Ribosome organizes, binds, and reads the provided sequence of nucleotides in mRNA

Afterward, catalyze the reaction to join AA to make protein chain

Endoplasmic reticulum is not found prokaryote

Question 16

Translation in prokaryotes vs eukaryotes

Answer 16

In prokaryotes translation take place as soon as mRNA comes off the DNA transcript

In eukaryotes it does not

Question 17

Ribosomes consists of 2 subunits

Answer 17

1-3 types of rRNA

Consist of 20-50 types of proteins

Eukary ribosomes are larger

Question 18

Reading codons

Answer 18

One of ribosomes key roles is to read codons in mRNA

Codons are groups of three nucleotides

Each codon (group of 3 makes 1 amino acid)

Met (methionine) - Start Codon initiated by AUG

Question 19

Transfer RNA tRNA

Answer 19

tRNA translate each codon in the mRNA into one amino acid

Anticodon matches with mRNA

Question 20

Translation steps (overview)

Answer 20

Initiation - AUG codon is recognized, and MET is the first amino acid in the polypeptide chain

Elongation - Amino acids are added one by one to the chain

Termination - Addition of amino acids stops, completed chain is released from the ribosome

Question 21

Translation steps (overview)

Initiation

Answer 21

Start codon - AUG

Start AA - MET

Initiation factor - complex of proteins

Question 22

Translation steps (overview)

Elongation

Answer 22

Once the next tRNA is in place, a dehydration synthesis reaction takes place

Dehydration synthesis reaction forms peptide bond between two amino acids

Question 23

Translation steps (overview)

Termination

Answer 23

Elongation continues until ribosome reaching stop codon

UAA, UAG, UGA (stop codons)

Protein release factor causes bond between polypeptide and tRNA to be broken

Small and large subunits dissociate

Question 24

Post-Translational Modifications (PTMs)

Answer 24

Resulting proteins from PTM can alter the phenotype of a cell

Protein folding is an essential component of their function

Improper folding can lead to unstable and destructive proteins

Question 25

Specialized cells

Answer 25

During development gene regulation and expression causes cells to become more specialized -process known as differentiation A newly fertilized egg can develop into a complete organism -Egg is totipotent (all)

Question 26

Stem Cells

Answer 26

As development progresses cells become more specialized The more cell divisions the less freeness Levels: Pluripotent - more Multipotent - many

Question 27

All stem cells:

Answer 27

Totipotent Pluripotent Multipotent

Question 28

Mutation Types - Small Scale

Answer 28

Point Mutations Insertions Deletions These may or may not lead to large scale affects dependent on: -What sequence is affected (expressed or not expressed?) -Length of sequence affected

Question 29

Point Mutations

Answer 29

Majority of DNA does not code for protein Point mutations are more likely to take place in this area

Question 30

Nonsense mutation

Answer 30

Creates a stop codon (Harmful)

Question 31

Insertions and Deletions

Answer 31

Can affect the entire sequence by shifting placement (frameshift mutation) The earlier on in the sequence, the more harmful the mutation

Question 32

Polyploidy(Ploidy - number of sets of chromosomes)

Answer 32

Polyploidy - more than two in a set of chromosomes In Humans it is rare, but problematic (Klinefelter, Down Syndrome) In some plants it is more common

Question 33

Mutagens

Answer 33

*Agents that result in damage to DNA, leading to increased chance of mutations *X-Ray *UV light *Cigarette smoking *Radioactive materials (Ex. Carbon-14, Uranium, Radon-222) *Cells can repair damaged DNA, but an excessive amount can leave in unrepaired DNA

Question 34

Genetic Variation and Mutations

Answer 34

Mutations are not always negative in population In apples mutations incidental and purposeful lead to more variety in color and taste

Question 35

46 Total Chromosomes

Answer 35

Two in each set