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Anatomy and Physiology I > Lesson 4 > Flashcards

Lesson 4 Flashcards

1
Q

nucleus

A

usually the largest organelle in the cell, contains genetic material

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2
Q

nuclear envelop

A

double membrane around the nucleus
perforated by nuclear pores

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3
Q

nuclear pores

A

formed by a ring of proteins called the nuclear pore complex, perforates the nuclear envelope

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4
Q

what do nuclear pores do for the nuclear envelope? (2)

A

regulates molecular traffic
holds the two membrane layers together

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5
Q

what supports the nuclear envelope?

A

a web of protein filaments called the nuclear lamina

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6
Q

nucleoplasm

A

the material within the nucleus

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7
Q

what comprises nucleoplams?

A

chromatin (DNA and proteins) and one or more nucleoli where ribosomes are produces

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8
Q

nuceleolus

A

area in the nucleus that is composed of RNA, enzymes and histones
abundant in cells that produce lots of proteins

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9
Q

what types of cells produce lots of proteins? (3)

A

ex. liver, nerve, and muscle cells

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10
Q

what does the nucleolus produce?

A

rRNA and ribosomal subunits essential for translation

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11
Q

ribosomes

A

composed of rRNA and ribosomal proteins, form subunits that are used in translation

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12
Q

what organelle shares it’s membrane with the nucleous?

A

the ER

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13
Q

deoxyribonucleic acid (DNA)

A

long, thread-like molecule with uniform diameter, varied in length

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14
Q

how many chromosomes are in the nucleus of most human cells?

A

46

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15
Q

DNA is comprised of polymers called…

A

nucleotides

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16
Q

three components of a nucleotide

A
  1. a sugar (deoxyribose or ribose)
  2. a phosphate group
  3. a nitrogenous base
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17
Q

purines

A

adenine and guanine
double-ringed structure

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18
Q

pyrimidines

A

cytosine, thymine, and uracil
single-ringed structure

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19
Q

bases are held together by what type of bonds?

A

hydrogen bonds

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20
Q

how many bonds does A-T make?

A

two

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21
Q

how many bonds does G-C make?

A

three

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22
Q

main function of DNA

A

carry instructions (genes) for the synthesis of proteins

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23
Q

gene

A

an information-containing
segment of DNA that codes for the production of a
molecule of RNA that most often plays a role in
synthesizing one or more proteins
functional unit of heredity

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24
Q

what roles do non-coding DNA play? (2)

A
  1. add to chromosome structure
  2. regulates gene activity
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25
Q

chromatin

A

fine, filamentous DNA material complexed with proteins called histones

26
Q

histones

A

proteins around which DNA winds
cluster in groups of eight molecules

27
Q

nucleosome

A

DNA wrapped around histones

28
Q

sister chromatids

A

two parallel filaments of identical DNA

29
Q

chromatids are joined at the _______

A

centromere

30
Q

kinetochores

A

protein plaques on each side of the centromere, play a role in cell divison

31
Q

DNA to mRNA is called….

A

transcription

32
Q

where does transcription occur?

A

in the nucleus

33
Q

mRNA to protein is called…

A

translation

34
Q

where does translation occur?

A

the cytoplasm

35
Q

what enzyme is used during transcription?

A

RNA polymerase

36
Q

what does RNA polymerase do in transcripton?

A
  1. binds to the start sequence in DNA, opens the helix
  2. reades bases from one DNA strand to build a complementary strand of mRNA
  3. rewinds the DNA helix behind it allowing a gene to be transcribed by several polymerase molecules
37
Q

pre-mRNA

A

“immature” RNA produced by transcription, needs to undergo splicing

38
Q

enzymes within the nucleus remove _____ and splice together _____

A

introns
exons

39
Q

translation

A

nucleotide language converted into amino acid language

40
Q

messenger RNA

A

carries code from nucleus to cytoplasm
has protein cap that is a recognition site for the ribosome

41
Q

transfer RNA

A

delivers a single amino acid to the ribosome
contains and anticodon

42
Q

ribosomes have three sites

A

E site, P site, and A site

43
Q

translation: initiation (3)

A
  1. ribosomes assemble with mRNA in the cytosol
  2. small subunit binds to the leader sequence of mRNA, and the large subunit joins
  3. when AUG is reached, protein synthesis begins and tRNA brings the first amino acid, methionine
44
Q

translation: elongation (4)

A
  1. the next tRNA brings a new amino acid and binds to the A site
  2. the ribosomes creates a peptide bond between the first and second amino acids
  3. the ribosome moves down the mRNA by one codon, the growing peptide is now attached to the tRNA in the P site
  4. process continues
45
Q

translation: termination (3)

A
  1. ribosome reaches a stop codon
  2. A site binds a protein called a release factor
  3. ribosome disassembles and dissociates from mRNA
46
Q

polyribosomes

A

ribosome clusters translating the same mRNA molecule simultaneously

47
Q

protein processing and secretion (6)

A
  1. protein formed by ribosomes on rough ER
  2. protein packages into transport vesicle which buds from the ER
  3. transport vesicles fuse into cluster to form a new cis cistern of the Golgi
  4. Golgi complex modifies the proteins
  5. trans cistern breaks up into cargo-laden golgi vesicles
  6. secretory vesicles release protein by exocytosis
48
Q

gene regulation example: casein

A
  1. hormone prolactin binds to receptors of mammary cells
  2. receptors trigger activation of a regulatory protein in the cytoplasm
  3. regulatory protein moves into the nucleus and binds to the DNA near the casein gene
  4. the binding enables RNA polymerase to bind to the gene and transcribe it, producing the casein mRNA
  5. the casein mRNA moves to the cytoplasm, binds to ribosomes, and starts translation
  6. the golgi complex packages casein into secretory vesicles
  7. the secretory vesicles release the casein by exocytosis, and it becomes part of the milk
49
Q

four steps of DNA replication

A
  1. unwinding the helix from histones
  2. unzipping small portions of the helix by DNA helicase, forming the replication fork
  3. DNA polymerase moves along each strand, synthesizing complementary strands
    • segments are connected by DNA ligase
  4. new histones are synthesized, used to organize new DNA strands into nucleosomes
50
Q

interphase - G1 - characteristics

A
  • interval between cell division and DNA replication
  • cell carries out normal tasks and synthesizes proteins and materials needed for the next phase
51
Q

interphase - synthesis - characteristics

A

cell replicated all nuclear DNA and duplicated centrioles

52
Q

interphase - G2 - characteristics

A

cell repairs DNA replication errors, grow, and synthesizes enzymes that control cell division

53
Q

G zero phase

A

cells that have left the cycle and cease dividing for a long time or permanently
ex. skeletal muscle cells, cardiac muscle cells, neurons

54
Q

prophase characteristics

A
  • genetic material condenses into compact chromosomes
  • nuclear envelope disintegrates
  • centrioles sprout spindle fibers
55
Q

metaphase characteristics

A
  • chromosomes aline on cell equator
  • spindle fibres form the mitotic spindle
  • centrioles complete a starlike aster which anchors itself into the cell membrane
56
Q

anaphase chracteristics

A
  • enzyme cleaves sister chromatids at centromere
  • single daughter chromosomes migrate to opposite sides of the cell
57
Q

telophase characteristics

A
  • chromosomes cluster
  • rough ER makes new nuclear envelope
  • chromosome uncoil
  • mitotic spindle disintegrates
  • each nucleus forms nucleoli
58
Q

cytokinesis characteristics

A
  • division of cytoplasm
  • starts in late anaphase
  • achieved by myosin proteins pulling on actin in the terminal web
59
Q

when do cells divide? (5)

A
  1. have enough cytoplasm for two cells
  2. have replicated their DNA
  3. have adequate supply of nutrients
  4. stimulated by growth factor, increase in MPF (M-phase promoting factor)
  5. neighboring cells die
60
Q

when do cells stop dividing? (3)

A
  1. snugly contact neighboring cells
  2. nutrients or growth factors are withdrawn
  3. experience contact inhibition
    • stopping of cell division in response to contact with other cells
61
Q

cachexia

A

severe wasting away of depleted tissues

Anatomy and Physiology I (22 decks)

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