Mod 1

Question 1

What are the 3 tenets of cell theory?

Answer 1

1) all living organisms are made up of fore than one cell
2) The cell is the basic unit of structure and organization in organisms
3) all cells come from pre existing cells

Question 2

What are some characteristics of prokaryotes ?

Answer 2

no nulceus or membrane bound organelle , smaller cells , are unicellular, binary fission, always asexual

Question 3

What are some characteristics of Eukaryotes

Answer 3

nucleus and membrane bound organelle , larger cells , multicellular, perform mitosis and meiosis, sexual and a sexual

Question 4

Hydrophilic

Answer 4

water being attracted to water

Question 5

Hydrophobic

Answer 5

does not dissolve in water, carbon is a good example

Question 6

the cell can form membranes because ?

Answer 6

non polar carbon is attracted to each other and will repel water allowing for compartmentalization to occur

Question 7

why can water support life ?

Answer 7

1)because of its polarity meaning that it is an excellent solvent and delivers the nutrients along with waste removal and allows chemical messengers
2) high specific heat capacity allows for thermoregulation which acts as a heat sink for the many chemical reactions

Question 8

central DNA dogma

Answer 8

3 key processes that must take place for information to turn into DNA and protein- consists of replication ( DNA is copied before cell division so each new cell will have DNA
Transcription- info from a section of DNA is transcribed into RNA to be transported out of the nucleus for protien production
RNA is read and processed and is translated into from nucleotides to amino acids

Question 9

What is meant by the DNA being semi conservative

Answer 9

The parent cell acts as a template for the daughter cell, meaning that the parent cell is semi conserved in the daughter cell

Question 10

3 process of DNA replication

Answer 10

initiation , elongation, termination

Question 11

replication consists of ?

Answer 11

DNA strands are being separated ( happens at areas in the DNA known as the origin of replication ( ORC)

Question 12

Steps in DNA replication

Answer 12

1) protein binding to the ORC DNA helicase is the most important
2) the 2 strands get unwound forming replication fork and helicase and the fork will move down the strand
3) exposed DNA can now be copied and synthesis of new strands can be carried out by DNA polymerase where primase will add RNA nucleotides at start of strand

Question 13

elongation replication stage

Answer 13

Primers here will get elongated by the enzyme DNA polymerase

Question 14

Direction of DNA polymerase

Answer 14

can move along the parent strand in 3’ to 5’ direction , creating strand in the 5 to 3 direction

Question 15

catalysis and DNA polymerase

Answer 15

will catalyze phosphdiester bonds between incoming nucleotide and existing one on backbone

Question 16

Direction of DNA Synthesis and what is made

Answer 16

5 to 3 direction and and one new leading strand which is a continuous piece while the other is in pieces known as the lagging strand

Question 17

Lagging strand is built in which direction ? why does it move away from the fork

Answer 17

5 to 3 direction running away from the replication fork and because DNA polymerase can only build continously in the 3 to 5 direction .As it moves away from fork , it must be released and reattached multiple times and each time will require primase

Question 18

Lagging strand is built in which direction ? why does it move away from the fork

Answer 18

5 to 3 direction running away from the replication fork and because DNA polymerase can only build continously in the 3 to 5 direction .As it moves away from fork , it must be released and reattached multiple times and each time will require primase

Question 19

What are okazaki fragments ?

Answer 19

short fragments of DNA created from the lagging strand

Question 20

What are SSPS ?

Answer 20

Binding proteins that protect the lagging strand from damage when it is not being replicated

Question 21

role of ligase ?

Answer 21

Where RNA primers used to be , ligase will connect and make the strand continuous. This is done by catalyzing phosphodiseter bonds which will seal the gaps in the backbone the lagging strand will be joined together

Question 22

problem with the termination of replication

Answer 22

there is a stretch of DNA on the lagging strand that cannot be replicated ( not enough space for primase to add RNA primer resulting in a stretch of uncopied dna known as overhang

Question 23

cell structures that prevent shortening of chromosomes

Answer 23

Telomeres are sections of non coding DNA that are added to the end of each chromosome which can be degraded over time because they are non functional

Question 24

Enzyme that adds telomeres

Answer 24

telomerase which carries RNA strand which can bind to the 3” overhang

Question 25

After non functional DNA is added ? what happens

Answer 25

RNA primer is added and DNA polyermase adds DNA until there is not enough on the 3 end

Question 26

What are some of the transcription factors? and what do they do ?

Answer 26

Involved in the synthesis of DNA to RNA( RNA polymerase ) There are 3 types of RNA polymerase in eukaryotes

Question 27

RNA polymerase 1

Answer 27

responsible for synthesizing most of the rRNA required for a functional ribosome

Question 28

RNA polymerase 2

Answer 28

synthesizes mRNA

Question 29

RNA polymerase 3

Answer 29

synthesizes tRNA

Question 30

Initiation of transcription and second step ?

Answer 30

- starts with the binding of a transcription factor to specific sequence which is known as a regulatory region located upstream of gene and can control if the gene is turned on or off - step 2, takes place when Pol II binds to the DNA and will attach to promoter

Question 31

promoter region

Answer 31

known as the start site for transcription and contains a TATA box

Question 32

the binding of transcription factors will carry out the process with what 3 mechanisms ?

Answer 32

1) guiding RNA pol2 to the correct DNA strand 2) unwinding the strand enough for RNA POL 2 to access the gene 3) activating the enzyme function of RNA pol 2 by phosphorylating it twice Then transcription

Question 33

transcription complex is made up of :

Answer 33

RNA pol 2 and transcription factors

Question 34

Elongation of transcription

Answer 34

when the polymerase moves forward it will synthesize mRNA molecule and RNA pol2 will add nucleotides to the 3' end of the growing strand

Question 35

transcription bubble

Answer 35

entire region of unwound DNA

Question 36

How does transcription end?

Answer 36

Proteins bind to pol 2 to halt transcription. Will end when RNA is cleaved from RNA pol2 by a seperate enzyme and the transcription bubble collapses and the RNA molecule disscociates from template and Pol 2 will detatch from DNA

Question 37

Why is post transcriptional RNA processing needed ?

Answer 37

- needed to preserve the newly formed mRNA molecule and deliver it to its final location

Question 38

5' methylguanosine cap

Answer 38

occurs shortly after the synthesis takes place, is used as a form of protection for the mRNA moleecule from degrading prematurely - required to begin translation

Question 39

3- polyadenylation

Answer 39

Poly A polymerase adds around 200 adenosines to the 3 ' end right after its cut from the RNA pol 2 ( creates poly A tail - needed for the binding of proteins so the mRNA can be transported out of the nucleus to start translation

Question 40

RNA splicing

Answer 40

occurs at the same time as the polyA tail - removal of the introns ( non coding regions of the gene , performed by spliceosome ( protein/ RNA complex )

Question 41

alternate splicing

Answer 41

creates multiple mRNA molecules from one gene causing exons to be skipped

Question 42

How does the mRNA get transported out of the nucleus

Answer 42

proteins bind to mRNA to transport out of nucleus through nuclear pore where the mRNA will then remain in cytoplasm

Question 43

Translation is initiated by ?

Answer 43

initiation factors which bind to the mRNA and will help the ribosomal subunits identify the initiation site

Question 44

Elongation factors

Answer 44

Proteins which help in elongation and some will form complexes to deliver tRNA

Question 45

job of tRNA

Answer 45

Deliver the correct amino acid to growing peptide where each one will recognize a codon and will have the complementary sequence ( anticodon )

Question 46

Ribosome

Answer 46

large and small subunit made of tRNA , LARGE one has 3 sites ( APE ) and small site bind the mRNA

Question 47

Initiation of translation

Answer 47

ribosome assembles around the tRNA , inititation factors help with this where they will bind to the poly A tail binding protein

Question 48

2 kinds of DNA repair

Answer 48

repair during DNA replication and repair in the cell cycle