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Bio 181 > Bio exam 4 > Flashcards

Bio exam 4 Flashcards

1
Q

During what process are parental DNA strands used as templates for the synthesis of new DNA strands?

A

DNA replication

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2
Q

Explain DNA replication

A

process of coping a DNA molecule, polymerization of DNA, takes ALL DNA in the cell and will copy ALL DNA (amount of DNA will be double)

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3
Q

explain what happens after 1 round of DNA Replication

A

the daughter DNA molecules are formed of one parental and one daughter strand

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4
Q

define semiconservative in DNA replication

A

one strand of old (parental) DNA and one strand of new (daughter) DNA

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5
Q

sketch a replication bubble and label on it the 5’ and 3’ ends, the origin of replication, replication forks, as well as the direction of the leading and lagging strands

A

do on paper

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6
Q

What is the origin of replication?

A

A sequence that indicates where to begin DNA replication

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7
Q

Explain DNA replication Bubble

A

2 replisomes will move right and left from the origin of replication, followed by 2 replication forks

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8
Q

What is a replication fork?

A

a Y-shaped region where new DNA symthesis is heppening.

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9
Q

describe the functions of helicase, topoisomerase, single-strand binding protein, primase, ligase, and DNA polymerases III and I

A

AHHH

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10
Q

What is the function of DNA helicase?

A

Breaks hydrogen binds between parental strands

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11
Q

What is the function of DNA Topisomerase?

A

cuts DNA, allowing DNA to unwind and then joining it

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12
Q

What is the function of single-strand binding protein?

A

Attach to a single strand DNA and prevent H=bonds from reforming

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13
Q

What is a finction of DNA primase?

A

Synthesizes a short sequence of RNA, primer for RNA

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14
Q

What is the function of DNA Polymerase 1

A

To remove the RNA primers and replace them with DNA

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15
Q

What is the function of DNA ligase?

A

Closes the Gap between Okazaki fragments, forming a phosphodiester bond.

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16
Q

What is the function of DNA polymerase 3?

A

to add nucleotide to the 3’ end of a growing DNA strand.

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17
Q

Explain the order that DNA replication happens in, including time

A

Time 1

  1. Helicase breaks down bonds between parental strands
  2. Single-stranded binding proteins attach to single stranded DNA and prevent H-bonds from reforming
  3. Topoisomerase cuts DNA, unwinding it
  4. Primase synthesizes a short, sequence of RNA
  5. DNA Polymerase III uses 3’ end to continue synthesis of the daughter strand

Time 2

Steps 1-3 are the same as the heading strand

  1. Primase sets the RNA primer down
  2. DNA Polymerase III extends the 2nd Okazaki fragment
  3. DNA polymerase I removes RNA nucleotide and replaces the RNA with DNA nucleotides

Time 3:

  1. Ligase closes the gap between Okazaki fragments and forms a phosphodiester bond
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18
Q

outline the key differences between the synthesis of the leading and lagging strands

A

on paper

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19
Q

What are characteristics of the leading strand?

A

synthesized 5’ to 3’, same direction of the replication fork synthesized in one continuous piece

20
Q

Identify characteristics of the lagging strand?

A

synthesized 5’ to 3’ discontinuously, in fragments, synthesized in the opposite direction of the replication fork.

21
Q

define what a chromosome is, explain the relationships between DNA, genes, chromosomes, sister chromatids, and centromeres

A

on paper

22
Q

define chromosomes

A

discreate units of genetics informations, can have many linear in eukaryotes, can have 1 circular in prokaryotes

23
Q

Define gene

A

segment of DNA that encodes for one protein

24
Q

Define homologous chromosomes

A

maternal and paternal of the same chromosomes type: will be the same order, shape, size

maternal= egg
paternnal= sperm

25
Q

What are x and y chromosomes?

A

sexyal chromosomes that carry info that determins biological sex of a person

XX female
XY male

26
Q

explain what the “n number” of a cell is as well as explain the difference between a haploid and a diploid cell

A

n= the number of chromosomes in each cell (humans n=23)
a haploid cell contains a single set of chromosomes
a diploid cell contains two copies of each chromosome

27
Q

Explain the difference between gametes and somatic cells

A

a gamete is a reproductive cell of an animal/plant
somatic cells are other cells that are not reproductive

28
Q

list the phases of the eukaryotic cell cycle and explain the major events that occur in each one (Section 14.1)

A

The cell cycle is divided into interphase and the mitotic phase

29
Q

Describe the stages/what happens in interphase

A

G1 phase: the cell grows physically larger and copies organelles

S Phase: the cell synthesizes a complete copy of the DNA in its nucleus and a centrosome

G2 Phase: the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis

30
Q

Give a general description of Mitosis

A

the nuclear DNA of the cell condenses into visible chromosomes and is pulled apart by the mitotic spindle, a specialized structure made out of microtubules.

31
Q

Give a general description of Cytokinesis

A

the cytoplasm of the cell is split in two, making two new cells. Cytokinesis usually begins just as mitosis is ending.

32
Q

What is a cleavage furrow and a cell plate?

A

A cleavage furrow in animals is created when the contractile ring pinches the cell into 2 separate parts
Since plant cells are harder, a plant cell will build a new structure down the middle of the cell, known as the cell plate

33
Q

Describe each stage of mitosis

A

Prophase: chromosomes condense, mitotic spindle begins to form, nucleolus disappears

Prometaphase: chromosomes are very compact, nuclear envelope breaks down, mitotic spindle grows more

Metaphase: the spindle has captured all the chromosomes and lined them up at the middle of the cell, ready to divide.

Anaphase: the sister chromatids separate from each other and are pulled towards opposite ends of the cell- driven by motor proteins

Telophase: mitotic spindle is broken down, new nuclei appear

Cytokinesis: pinching the cell in two like a coin purse with a drawstring and separating the two cells

34
Q

explain the role of mitosis and meiosis processes in the life cycle of a vertebrate animal as well as label the haploid and diploid phases, the time of fertilization and formation of the zygote

A

on paper

35
Q

outline the key events that occur during the phases of meiosis

A

on paper

36
Q

Define and describe phases of Meiosis I

A

Prophase I: Crossing-over occurs (homologous chromosomes pairing up)

Metaphase I: homologue pairs line up at the metaphase plate

Anaphase I: homologues separate to opposite sides of the cell, sister chromatids stay together

Telophase I: Newly forming cells are haploid (n=2), each chromosome has two non-identical sister chromosomes

37
Q

Define and describe each phase of meiosis II

A

prophase II: the nuclear envelope dissolves and chromosomes condense

metaphase II: chromosomes line up along the cell’s middle (metaphase plate)

anaphase II: sister chromatids separate and move to opposite ends of the cell

telophase II: the nuclear envelope reforms, and the cell splits into four new cells, each with a haploid number of chromosomes.

38
Q

explain the process of crossing over (source of genetic variation)

A

crossing over is a reciprocal exchange between non sister chromatids within a pair of homologous chromosomes. it takes place during prophase I and happens at least one per pair of human homologs.

39
Q

Define chiasma

A

site of crossing over

40
Q

crossing over will leave 4 chromosomes, 2 being strictly paternal/maternal, called ____ and two being a combination of both, called ___

A

maternal/paternal : non-recombinant chromosomes
combinations of both : recombinant chromosomes

41
Q

explain the role of crossing over, independent assortment, and random fertilization in increasing genetic diversity

A

on paper

42
Q

define independent assortment

A

chromosomes sort at random during meiosis I between daughter cells, can be maternal or paternal

43
Q

if we have a 2n=4 cell, how many different ways are possible to arrange the cell?

A

2^n = 2^2 = 4 different ways of arranging cells

44
Q

if humans have n=23, how many different ways are possible to arrange the cell?

A

2^23 = 8.4 million different ways

45
Q

Define fertilization and how this increases genetic diversity

A

fertilization is when gametes fuse at random, independent of the gametes genetic information.
the odds of a human zygote having a similar genetic are-
egg (1/8.4 mil) x sperm (1/8.4 mil) = zygote (1/70.6x10^12)
we are very genetically diverse!

Bio 181 (5 decks)

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