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MLS 4151 - Molecular Diagnostics > Wk. 2 | Replication, Cell Cycle, and Recombination > Flashcards

Wk. 2 | Replication, Cell Cycle, and Recombination Flashcards

1
Q

Recombination is a natural process in eukaryotes and prokaryotes to

A

produce offspring with new genetic combinations (recombinants)

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2
Q

Recombinant organisms are naturally produced in eukaryotes by

A

sexual reproduction

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3
Q

Recombinant organisms are naturally produced in prokaryotes by

A

gene transfer through:
- conjugation
- transduction
- transformation

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4
Q

Recombination in sexually reproducing organisms (eukaryotes) occurs via

A

Crossing over (physical exchange) between chromosomes resulting in a new combo of parental genomes

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5
Q

________ ______ is based on Mendel’s law

A

Crossing Over

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6
Q

Advantage(s) of Crossing Over

A

↑ robustness and adaptability of offspring (heteresis)

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6
Q

Heteresis

A

Hybrid vigor. Mixed individuals are stronger than purebred organisms

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7
Q

How does recombination occur? (3 steps)

A
  1. Meiosis: Duplicated homologous chromos line up and cross over
  2. Recombined duplexes are randomly assorted into gametes. Each gamete contains one set of the recombined parental chromosomes
  3. The gamete merges with a gamete from other parent carrying its recombined chromosomes resulting in offspring with a recombination of parental genes
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8
Q

Step 1: Meiosis: _____ _______ _______ line up and cross over

A

duplicated homologous chromosomes

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9
Q

Step 2: ______ ________ are randomly assorted into _______.

Each gamete contains…..

A

Recombined duplexes, gametes

1 set of recombined parental chromosomes

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10
Q

Step 3:
- The gamete merges with a……..

  • resulting in offspring with
A

a gamete from other parent carrying its recombined chromosome

a recombination of parental genes

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11
Q

Conjugation
- F+ and F- cells conjugate through a ______
- F- cells become F+ as __________________
- Both cells synthesize __________________
- Cells, now both F+ separate

A
  • bridge
  • it obtains a copy of F factor
  • a complementary DNA strand
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12
Q

Transduction
- __________ ________ ___________ _______ and transfer genetic info

A

Bacteriophages infect bacterial cells

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13
Q

Bacteriophages play a role in

A

transduction

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14
Q

Transformation
- Transfer of DNA from __________

  • _________ cells take up _____ DNA fragments
  • ___________ occurs between ________ and ______
  • Unrecombined DNA is ________
  • Results in a ____________ ___________ cell
A
  • one organism to another
  • Recipient, donor
  • Recombination occurs between donor + recipient DNA
  • Degraded
  • Genetically transformed
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15
Q

DNA Supercoiling

A

DNA is negatively supercoiled (under winding)

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16
Q

Supercoiling is beneficial because it aids these 2 things by….

A

Replication and Transcription

by lowering energy required to separate helix

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17
Q

Supercoils are mintained in eukaryotes by

A

the winding of the helix around histones

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18
Q

Generally, how is DNA replicated?

A

DNA duplicated from mother cell -> 2 identical copies

During division, each daughter cell gets 1 complete DNA copy

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19
Q

Difference between prokaryotic replication and eukaryotic replication

A

Prokaryotes: 1 origin of replication
Eukaryotes: Several origins -> several replications happening simultaneously

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20
Q

What is semi-conservative replication?

A

Half of original DNA is conserved

One daughter cell has original right strand and the other has the original left strand

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21
Q

How is DNA held together?

A

H bonding and twisting around each other

DNA inside a cell is supercoiled

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22
Q

Before separating, what has to be unwound?

A

BOTH the supercoils and the double helix

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23
Q

____________ unwinds supercoils

A

Topoisomerases

24
Q

What does gyrase do

A

Cuts both strands of dsDNA while holding two ends

25
Q

How are the two strands of DNA rejoined

A

two halves of strands rotate and the ends are rejoined

26
Q

Helicase does _________ by _________

A

unzips DNA strands
disrupting H bonds between base pairs

27
Q

DNA Replication in Eukaryotes
1. Replication at ____
2. Forks move in _________ ________ as DNA is synthesized

A
  1. ori
  2. opposite directions
27
Q

DNA Replication in Bacteria
1. ________ of parental DNA
2. ________ of the DNA strands ahead of the ___________ ______
3. _________ ______ serves as a swivel to allow _________ _________ of DNA strands
4. Binding of ___________ ______________
5. Synthesis of ___ _______ and unwinding of DNA by ________ and single-stranded binding proteins.
6. Formation of ___ __________ _________ in circular DNA and it is replicated.

A
  1. Unwinding
  2. Twisting, replication fork
  3. Transient breaks, free rotation
  4. initiation proteins
  5. RNA primers, helicase
  6. 2 replication forks
28
Q

Parental divorce

A

Single stranded binding proteins prevent two strands from getting back together during replication

29
Q

DNA Polymerase III
- Adds _________ to the __ __ end of the _________ strand

  • Elongates toward replication fork (__ to __)
  • More primers attach to opposite strand and elongates __ to __
  • This strand is the ________ strand
A
  • nucleotides, 3’ OH, original
  • 5’ to 3’
  • 5’ to 3’
  • lagging strand
29
Q

Creation of New Strand
1. Strands unwound.

  1. _______ binds and make ___ primers molecules.
  2. Primers attach to DNA at ___ and then begin a _______ strand.
A
  1. Primase, RNA
  2. ori, leading
30
Q

Replication ALWAYS occurs in this direction

A

5’ to 3’

31
Q

DNA Polymerase I
- An ________ enzyme
- Attaches to ______
- _____ strand ahead while __________ strand behind
- Replaces all _________ with deoxynucleotides

A
  • editing
  • nicks in growing strands
  • Edits, elongating
  • RNA nucleotides
32
Q

Leading Strand

A

5’ to 3’
made continuosly

33
Q

Step 1 of DNA Replication

A

Helicase unzips double helix

33
Q

Lagging Strand

A

3’ to 5’
made in short okazaki fragments and joined

34
Q

Step 2 of DNA Replication

A

SSBs stabilize unwound DNA

35
Q

Step 3 of DNA Replication

A

Leading strand synth. 5’ to 3’ by DNA polymerase

36
Q

Step 4 of DNA Replication

A

Lagging strand synthesized in segments

Primase makes RNA primers extended by DNA polymerase to form an okazaki fragment

37
Q

Step 5 of DNA Replication

A

RNA primer replaced by DNA
Ligase joins Okazaki fragments

38
Q

What enzyme joins Okazaki fragments

39
Q

Function of ligase

A

Acts like a glue, seals nicks

40
Q

Function of editing endonucleases

A

Replaces mismatched nucleotides with proper matches

41
Q

Function of gyrases

A

restores negative supercoils

42
Q

Function of methylases

A

Add methyl groups to new DNA at same spot as original

43
Q

Bacterial Cell Division
_______, ________ chromosome(s).

Replication proceeds at the same time in ____ direction.

Two ________ _____ will meet and merge.

Yields: __ ___ _______ chromosome(s).

___ chromosome(s) is in each cell when it divides.

A
  • Single, circular
  • both
  • replication forks
  • 2 new circular
  • 1
44
Q

Eukaryotic Cell Division
____ complex; ________ chromosome(s).

Inside nucleus is where related to the cell?

_____ chromosome(s), usually very ____

Several ____________ _______ along the length of each chromosome.

A
  • More, multiple
  • separated by nuclear membrane
  • Linear, long
  • replication forks
45
Q

Mitosis
1. _______ of mother cell is disassembled
2. Mother divides and _________ are divided between daughters
3. ___________ built around the chromosomes in each daughter cell

A
  1. Nucleus
  2. chromosomes
  3. New nucleus
46
Q

What phase of the cell cycle does DNA replicate in?

A

Interphase or S phase

47
Q

Phases of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

47
Q

Prophase

A

condensed chromsomes become visible and nuclear membrane dissolves

48
Q

Metaphase

A

Chromosomes move to cell equator and align in pairs

49
Q

Anaphase

A

Separate halves of each chromosome are drawn apart by the spindle fibers toward the poles of the cell

50
Q

Telophase

A

A new nuclear membrane is made to surround each set of newly divided chromosomes

50
Q

During meiosis, cells go from ______ to ______

A

diploid to haploid

51
Q

Diploid vs. Haploid

A

Diploid (2n)
- 46 chromosomes
- Somatic (non-sex) cells

Haploid (n)
- 23 chromosomes
- Germ cells or gametes (sperm + egg)
- Fertilization joins sperm and egg and restores 46 chromosomes

52
Q

Mitosis
_____________ duplicates DNA and splits it up into 2 genetically ___________________________

_______ cells.

A

1 diploid cell (2n), identical diploid cells (2n).

somatic

53
Q

Meiosis
1. Chromosomes replicate ____ in _ phase into sister chromatids. Cell divides _____

  1. During PMAT I, __________________ are segregated into different cells. 2 cells each have a copy of ______________
  2. Crossing over occurs during ______ to ___________. Homologs separate and chromosomes become part of _________
  3. During PMAT II, sister chromatids are _____________, so each of the daughter cells now have a _________________ and are now _________

This is how _____________ is generated.

A
  1. once, S phase, twice
  2. homologous chromosomes, each of the 23 chromosomes.
  3. PMAT I, shuffle the genomes, gametes
  4. pulled apart again, copy of each of the chromosomes, haploid

genetic diversity!

MLS 4151 - Molecular Diagnostics (3 decks)

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