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Biology 30-1 > Cell Division > Flashcards

Cell Division Flashcards

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1
Q

What is uncoiled DNA called?

A

Chromatin

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2
Q

What is chromatin?

A

A ball of uncoiled DNA found in nucleus, before division

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3
Q

What occurs to chromatin when cells divide?

A

They coil into organized structures known as chromatids

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4
Q

What is a single chromatid also known as?

A

Single chromatid = single stranded chromones

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5
Q

How many chromosomes are in a somatic cell? What is a somatic cell?

A

A somatic cell is any cell apart from the gamete cells (sperm/eggs)
- Has 46 chromosomes, AKA diploid, 2n

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6
Q

How many chromosomes are found in the gamete cells?

A

23, AKA haploid, n

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7
Q

What is produced when DNA replicates?

A

Produces a double stranded chromosome, (two chromosomes), AKA sister chromatids

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8
Q

What are the 3 phases of the cell cycle + their purpose?

A
  1. Interphase- 90 % of cell cycle, growth/dna replication
  2. Mitosis- divide genetic material
  3. Cytokinesis- divide cytoplasm
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9
Q

What is the purpose of the cell cycle?

A
  • Growth
  • asexual reproduction
  • tissue repair
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10
Q

What is interphase?

A
  • 1st step, prepares cell for divison
  • has 3 phases

G1- growth phase, makes new organelles, proteins, etc (translation and transcription occurs here)

S- synthesis- DNA replication, makes an extra copy of chromosome

G2- growth, last prep for cell division

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11
Q

What is mitosis?

A

Has 4 phases for dividing genetic material

  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
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12
Q

What occurs in prophase?

A
  • Chromatic coils to make chromatids (sister chromatids)
  • Spindle fibers form
  • centrioles move to poles of the cell
  • nuclear membrane dissolves
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13
Q

What conjoins sister chromatids?

A

Centromere

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14
Q

What occurs in metaphase?

A
  • Sister chromatids line up on equator of cell

- spindle fibers attach to centromeres

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15
Q

What occurs during anaphase?

A
  • Spindle fibers and centrioles pull sister chromatids apart to opposite sides of cell
  • (double stranded chromosomes turn back into single stranded chromosome cells)
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16
Q

What occurs in telophase?

A
  • Chromatids relax back into chromatin
  • nuclear membrane reforms
  • cell membrane begins to develop

(cleavage begins)

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17
Q

What is Cytokenesis?

A
  • 3rd phase of cell division
  • separation of cytoplasm
  • begins in anaphase, continues through telophase, and completes at end or mitosis
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18
Q

What is left at the end of the cell division process?

A

Two identical daughter cells w/ chromatins

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19
Q

What does ploidy mean?

A

The number of sets of chromosomes in a cell ie: Chromosome 21 has pair or single chromosome?

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20
Q

What is a diploid?

A

Each chromosome has a pair, ie: 23 pairs, 46 chromosomes

Somatic cells= every cell in the body apart from gametes are 2n

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21
Q

What is haploid?

A

When a chromosome is single, and has no pairs

1 of each chromosome due to meiosis,

23 chromosomes= n

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22
Q

What is meiosis?

A

The process that makes gamete/sex cells ie: oogenesis/ spermatagenosis

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23
Q

Why is meiosis important?

A
  • reduces the ploidy (number of sets) 2n-n in order for the zygote to only have 46 chromosomes

-

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24
Q

How many times does the cell divide in meiosis?

A

There are 2 divisions that occur, but only one DNA replication

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25
Q

What is a homologous pair?

A

-Paired chromosomes that are the same length, genes, and in the same order (one from mom, one from dad)

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26
Q

What is the process of synapsis?

A

When replicated homologous chromosomes form a tetrad (See diagrams)

tetrad: homologous chromosomes that have been replicated, so 4 chromatids are together

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27
Q

What is the process of crossing over?

A
  • The breaking and rejoining of homologous chromosomes, genetic info meshes together
  • increases genetic variation, all chromatids are different from each other
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28
Q

What are the steps to meiosis?

A
  1. interphase
  2. Meiosis I
    - prophase 1
    - metaphase 1
    - anaphase 1
    - telophase 1
  3. cytokinesis 1
  4. meiosis 2
    - prophase 2
    - metaphase 2
    - anaphase 2
    - telophase 2
  5. cytokinesis
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29
Q

What occurs during interphase of meiosis?

A
  • DNA replicates, cell grows

- This only occurs ONCE during meiosis, before meiosis I

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30
Q

What is a non recombinant chromosome?

A

The part of the chromosome that has not exchanged genetic information

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31
Q

What occurs during prophase 1?

A

-chromatin condenses to chromatids, connects via centromere (starts with 46 chromosomes)

  • nuclear membrane dissolves, spindle fibers form, centrioles to poles
  • replicated homologous chromosomes pair up to form a tetrad
  • “crossing over” occurs (exchange genetic info)
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32
Q

What is a tetrad?

A

homologous chromosomes that have been replicated that pair up with another = 2 chromosomes, 4 chromatids

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33
Q

What is metaphase 1?

A
  • tetrads line up together on the equatorial plate

- spindle fibers attach to centromeres

34
Q

What is anaphase 1?

A
  • Homologous chromosomes is pulled apart

- diploid -> haploid

35
Q

What is telophase 1?

A
  • nuclear membrane reforms
  • chromatids relax into chromosomes
  • cleavage begins
36
Q

What is cytokinesis 1?

A
  • cleavage begins
  • 2 daughter cells = haploid double stranded chromosomes
  • not genetically identical
37
Q

What occurs in meiosis 2, prophase 2?

A
  • Chromatin=chromatids

- nuclear membrane dissolving

38
Q

What occurs in metaphase 2?

A
  • double stranded chromosomes line up on equatorial plate

- spindle fibers attach to centromeres

39
Q

What occurs in anaphase 2?

A

-sister chromatids separate (doubles stranded chromosomes become single stranded chromosomes)

40
Q

What occurs in telophase 2?

A
  • chromatid = chromatin
  • nuclear membrane reforms
  • cleavage begins
41
Q

What occurs in cytokinesis 2?

A

-cytoplasm finishes cleavage
- 4 genetically different daughter cells
(haploid- 23 chromosomes)

42
Q

How does the formation of gametes occur?

A

Both occur using meiosis to make haploid gametes

43
Q

What does spermatogenesis create?

A
  • cell divides into two haploid cells which divide into 4 sperm cells
  • equal distribution of cytoplasm between daughter cells

(quantity over quality)

44
Q

How does oogenesis occur in terms of cell division?

A
  • Primary oocyte divides into secondary oocyte and polar body, which divides into ovum and polar body, and the other polar body splits into 2 other polar bodies (3 polar bodies, 1 egg)
  • unequal distribution of cytoplasm between daughter cells
  • polar bodies eventually dissolve

(quality over quantity)

45
Q

What is nondisjunction?

A
  • abnormal meiosis
  • occurs when homologous pairs or sister chromatids don’t separate properly during anaphase 1 or anaphase 2, respectively
46
Q

What is a trisomy?

A
  • one extra chromosomes

ex: trisomy 21 = extra chromosome 21 = down syndrome

47
Q

What is a monosomy?

A
  • one less chromosome (45)

ex: turners syndrome=one x chromosome only

48
Q

Know diagrams for anaphase 1 and anaphase 2 nondisjunction

A
49
Q

What is DNA made up of?

A

DNA is made up of nucleotides, which are composed of phosphate, deoxyribose sugars, and nitrogenous bases (purines/pyrimidines)

50
Q

What does phosphate do in nucleotides?

A

Phosphates (po43) makes the DNA negatively charged

51
Q

What do the nitrogenous bases do?

A

They keep the 2 strands of the dna together, held together by hydrogen bonds

52
Q

What are the two types of nitrogenous bases?

A

Purines - Adenine and Guanine

Pyrimidines- Thymine and Cytosine

53
Q

What forms the backbone of the DNA double helix? What bonds hold them?

A

Sugar phosphate backbone, which holds the nucleotides together
They are held together by phosphodiester bonds

54
Q

In what direction are the backbones made?

A
  • in the 5’ to 3’ direction,

- Travel anti parallel

55
Q

What are the complementary bases on a DNA strand?

A
  • A binds to T

- G binds to C

56
Q

What are the differences of RNA from DNA?

A

Rna is:

  • single stranded
  • has ribose sugar
  • Instead of T, A binds with U
  • Not stored in the nucleus
57
Q

Where does DNA replication occur?

A

This occurs in the nucleus

58
Q

What does it mean to say that DNA replication is semi-conservative?

A

Each DNA molecule that has been replicated has one Og strand, and one new strand

59
Q

What is the 1st step for DNA replication?

A
  1. DNA unwinds/unzips

- Enzyme helicase creates a replication fork by breaking hydrogen bonds between nitrogenous bases

60
Q

What is the 2nd step for DNA replication?

A
  1. DNA polymerase binds exposed strand+ builds new strands in 5’ to 3’ direction
    - Fork splits into leading strand and lagging strand
    leading strand: built continuously (dna polymerase moves towards replication fork, built antiparallel)
    lagging strand: made non continuously, dna polymerase moves away from replication fork
61
Q

What is the 3rd step?

A

Dna polymerase proofreads + fixes any mutations

62
Q

What is the 4th step for DNA replication?

A

DNA ligase connects phosphodiester bonds in backbone of fragments

63
Q

During what phase does DNA replication occur?

A

The S phase on interphase

64
Q

During what phase does transcription and translation occur?

A

During the G phases of interphase

65
Q

Which two steps occur to create a polypeptide chain?

A

Transcription and transation

66
Q

Where is and what occurs during transcription?

A

Occurs in the nucleus, purpose is to transcribe a gene in DNA onto an mRNA strand so it can leave the nucleus

67
Q

What are the three steps to transcription?

A

a) initiation
b) Elongation
c) termination

68
Q

What occurs during initiation of transcription?

A

-RNA polymerase binds to a promoter region ahead of gene to be transcribed (helicase assists to unzip and unwind)

69
Q

What occurs during elongation phase of transcription?

A
  • RNA polymerase builds on mRNA strand in 5’ to 3’ direction (Uses 3’ to 5’ as template)
  • must be antiparallel but develop in the 5 to 3, so it uses to 3 to 5 as a template for complimentary bonds, however builds in the 5 to 3 direction
70
Q

What occurs during the termination phase of transcription?

A
  • RNA polymerase reaches ‘stop’ sequence in the proteins
  • mRNA peels away and leaves nucleus
  • mRNA polymerase falls off
  • DNA rezips and rewinds
71
Q

What is the difference between nucleotides in transcription and replication?

A 
Replication= GCAT
Transcription= GCAU
72
Q

What are the three steps to translation?

A

Initiation, elongation, termination

73
Q

What occurs during initiation?

A
  • Ribosome binds at the start codon (AUG) on mRNA

- Brings in tRNA

74
Q

What occurs during elongation?

A
  • tRNA molecules will bind complementarily with codons on mRNA
  • Amino acid on tRNA transfers to the growing polypeptide chain
  • EMPTY tRNA leaves ribosome, new tRNA inds
75
Q

What occurs during termination?

A

-Ribosome reaches STOP sequence/codon= ribosomes falls off, polypeptide released (mRNA is recycled)

76
Q

What are the kinds of DNA technologies?

A
  • Mitochondrial DNA
  • cloning
  • Gene therapy
  • Recombinant DNA
  • DNA finger printing
77
Q

What is mitochondria DNA?

A
  • inherited from maternal side (organelles+cytoplasm in zygote come from egg)
  • little variation as there is no crossing over between DNA in the mitochondria
78
Q

What is cloning?

A
  • offspring is genetically identical to parent

- Nucleus of egg is removed, replaced with somatic (diploid) cell, zygote implanted, develops, birthed

79
Q

What is gene therapy?

A
  • Replacing defective genes with healthy ones
80
Q

What is recombinant DNA?

A
  • DNA molecule that has DNA fragments from multiple organisms
  • Used to produce hormones, proteins, etc (outside of body ie: for production of insulin)
81
Q

What is DNA finger printing?

A

-2 phases
- PCR - polymerase chain reaction
amplifies a section of DNA, makes many copies
Gel electrophoresis
- separate fragments of DNA based on size,
- DNA moves from negative terminal to positive terminal

Biology 30-1 (6 decks)

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