Test 2 study set

What is the first step in DNA replication?

The initiator protein binds to the origin

What is the second step in DNA replication?

Helicase unwinds the DNA

What is the third step in DNA replication?

Primase synthesizes an RNA primer

What is the fourth step in DNA replication?

DNA polymerase synthesizes the newly replicated strand in a 5' to 3' direction

What is the fifth step in DNA replication?

DNA exonuclease removes misplaced nucleotides in the newly replicated strand

What is the sixth step in DNA replication?

Ligase seals up the nicks in the lagging strand

Why is DNA ligase important for a cell?

It joins Okazaki fragments.
It joins DNA together from different origins of replication.

Energy is required in order to add a nucleotide to the growing strand of DNA during replication. From where does that energy come?

The incoming nucleotide

What is DNA polymerase?

an enzyme that is a critical component of a large protein complex that carries out DNA replication

What is the role of DNA polymerase in replication?

synthesizes the new DNA 5' to 3'. Also proofreads

How is the bond made in replication?

It is a phosphodiester bond which are covalent bonds. The new bond is made 5'-3'.

How does DNA replication relate to properties of life?

-Self Replicating
-Follows and stores instructions (translation and transcription)
-Evolving(Mutation is the source of variation)

What direction are new DNA strand made?

5'-3'

What is the role of the 3OH in the incoming nucleotide?

3OH of the growing strand attacks the first phosphate of the incoming nucleotide

What is the replication fork?

a Y-shaped region where new DNA strands are elongating. Semi conservative.

What is DNA replication?

When DNA makes a copy of itself

What is the process of DNA replication?

the strands unzip, the nucleotides pair up according to the base pairings, and then DNA polymerase connects them

What is proofreading?

the removal of non-complementary nucleotides incorporated during DNA replication

What is Okazaki Fragments?

Any of the many short DNA pieces in the lagging strand

How are Okazaki Fragments bound back together?

DNA ligase joins the two DNA fragments in lagging strands

What are leading strands?

A daughter strand that has its 3' end pointed toward the replication fork, so as the parental double helix unwinds, this daughter strand can be synthesized as one long continuous polymer

What are lagging strands?

A daughter strand that has its 5' end pointed toward the replication fork so as the parental double helix unwinds, a new DNA piece is initiated at intervals and each new piece is elongated at its 3' end until it reaches the piece in front of it

What is a replication bubble?

an unwound and open region of a DNA helix where DNA replication occurs

What is the origin in DNA replication?

a specific sequence of DNA where DNA replication begins

The polarity of DNA synthesis is

always 5'-3'

What role does the polarity of DNA synthesis play in replication?

Because the parental DNA strand is antiparallel and the new DNA can only be made 5' to 3' the two daughter strands are made differently

What type of conservativity is replication?

Semi-conservative... meaning there is one strand of the parent strand and one daughter strand

How do DNA and RNA differ?

RNA has a different 3' sugar than DNA. RNA has a uracil base instead of a thymine base. RNA is single stranded.

What is the central dogma?

(Replication) DNA -> RNA -> Protein

What is transcription?

DNA double strand is unwounded and the promoter is an indicator of coding strand and template strand. Then RNA polymerase makes the mRNA.

What are transcription factors?

regulatory proteins that bind to specific DNA sequences

How do genes vary in expression?

All cells have the same genes. Different cell types express different genes and also make different proteins

Where is the template strand?

The strand that goes in the opposite direction of the promoter

What is the coding strand?

The strand that goes in the same direction as the promoter. Also has a similar code to the promoter/mRNa

Where does the incoming strand attach in transcription?

It attaches to the template strand

What enzyme facilitates transcription?

RNA polymerase

What is the base that replaces DNA in RNA?

Uracil

What directionality is the new strand made in transcription?

5 end to 3 end

What two factors that were true in replication are also true in transcription?

Both processes use DNA as a template and phosphodiester bonds are formed in both cases

How is the RNA-DNA duplex different from the replication bubble?

It is complementary and antiparallel

What is the promoter region and how does it relate to transcription

The sequence of the promoter region determines which transcription to the promoter region factors bind

What determines when, where, and how much gene is transcribed?

The sequence of the promoter

How does transcription begin?

RNA polymerase attaches to the promoter region

What is the process of transcription?

DNA strand begins to unwind a segment of DNA molecule until the two strands separate. RNA polymerase uses one strand to string together a complementary strand of RNA nucleotides. DNA helix zips back together. When finished, RNA strand detaches completely from the DNA.

What are the three steps of transcription?

initiation, elongation, termination

What are the 3 crucial "things" involved transcription?

5' cap is added, introns are excised from the RNA strand and exons are spliced together, Poly A tail

What stores the instructions for cellular work?

DNA

What directs the productions of proteins?

mRNA

What provides structure and essential activities in a cell?

Proteins

What is an intron?

Introns are IN the way, and need to get out

What are exons?

Exons are EXpressed

What is alternative splicing?

mRNA processing events that lead to different combinations of exons being spliced together

How many bases specify one amino acid?

4

How many bases and amino acids are there?

4 bases, 20 amino acids

What is translation?

Synthesis of a polypeptide chain corresponding to the coding sequence present in a molecule of a mRNA

How are ribosomes "read" by a ribosome?

mRNA are "read" by a ribosome in 3 nucleotide units, termed codons

What is a codon?

group of 3 mRNA bases

What is the start codon?

AUG

What are the stop codons?

UAA, UAG, UGA

What are the characteristics of the genetic code?

RUNNC-
1. Redundant
2. Unambiguous
3. Non-overlapping
4. Nearly Universal
5. Conservative

What are the three main types of RNA?

mRNA, tRNA, rRNA

What are the components of translation?

mRNA, Initiation, elongation, and release factors

How is the process of translation completed? What are the four steps?

1. AUG
2. Initiation (scans mRNA for AUG codon)
3. Elongation (forming a peptide bond)
4. Termination (stop codon and then release factor)

What is the rRNA composition and structure?

It's a large subunit and small subunit of APE

What are the the EPA sites? What do they do?

- A site lets tRNA into the ribosome
- P site holds the polypeptide-bonded amino acids
- E site ejects the tRNA no longer holding the polypeptide

What direction is translation/mRNA read and how does that affect the directionality of the growing polypeptide?

5' to 3' and it causes the polypeptide to grow in the N' to C'

What is the process that the amino acid is brought to the ribosome, and through the EPA sites?

The tRNA holds the anticodon that binds to the codon on mRNA and this causes the amino acids to form all together into a polypeptide until they meet a stop codon.

What properties of life are the cell cycle (and mitosis) involved in?

-Self-Replicating
-Controls its functions and responds to the environment

What is the Cell Cycle?

The regular sequence of growth and division that cells undergo

What stages are involved in the cell cycle?

G1, S phase, G2, M phase, Cytokinesis

G1 phase

The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.

S phase

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.

G2 phase

The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.

M phase

mitosis and cytokinesis

What is Mitosis?

Cell division that generates new cells for growth and repair. The division of one cell into two genetically identical daughter cells

What are the stages involved in mitosis?

prophase, prometaphase, metaphase, anaphase, telophase

Why is Mitosis important?

Growth and reproduction

What process is Mitosis involved in?

DNA replication

What is the point of mitosis?

to make identical daughter cells

What is cytokinesis?

the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells.

How is the central dogma involved in the cell cycle?

Translation and Transcription happen in cells

When, in the cell cycle, might the DNA be decondensed? Condensed?

Interphase- Decondensed
M phase- Condensed

What is a chromosome?

long linear DNA double helix wrapped around proteins

What are homologous chromosomes?

Two genetically similar chromosomes, one from each parent

What is a haploid cell?

Cells that have one set of all genetic info (in humans and most animals gametes are haploid)

What are diploid cells?

Cells that have two sets of genetic information (In humans and most animals, cells are diploid)

What is a centromere?

The centromere holds the sister chromatids together (made of protein)

What are Mendel's laws?

Law of Dominance
Law of Independent Assortment
Law of Segregation

What do separate colors, and sizes of the homologous chromosomes indicate?

When they are different colors but the same size, they are homologous chromosomes, but when they're the same color but different sizes, they are sister which are identical

What is the result of meiosis?

4 haploid daughter cells

What is the result of mitosis

two identical daughter cells

What is the Law of Segregation?

half the gametes receive one allele of a gene and half receive the other allele

What is Meiosis?

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

What are the stages of meiosis?

Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II

How does Meiosis differ from Mitosis?

Meiosis produces cells that are genetically different. Mitosis produces cells that are genetically identical.

What is the purpose of Meiosis?

produce gametes

What are the main events that happen from both Meiosis I and Meiosis II?

Meiosis 1 is the REDUCTIVE division homologs separate. Meiosis 2 is like mitosis except the cells are haploid and sisters are not identical

What occurs in each stage of Meiosis I?

Pro: Synapsis Crossover
Prometa: spindles attach to kinetochores
Meta: Homologous pairs line up in the center
Ana: homologous chromosomes separate
Telo/cyto: daughter cells are haploid

What occurs in each stage of Meiosis II?

Prophase: nuclear envelope disappears
Prometa: spindles attach to kinetochores
Meta: Chromosomes line up in the center
Ana: centromeres split, sister chromatids separate
Telo/Cyto: nuclear envelope reforms, cytoplasm divides

When does crossover occur?

Prophase 1