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Anatomy > Lecture 4 - Protein Synthesis > Flashcards

Lecture 4 - Protein Synthesis Flashcards

1
Q

What is Chromatin?

A

Threadlike material that makes up the chromosomes

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2
Q

What is a heterochromatin?

A

Highly condensed, and genes are INACTIVE

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3
Q

What is a Euchromatin?

A

extended form and is ACTIVE in genetic transcription (RNA synthesis)

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4
Q

What makes up a nucleosome?

A

Histone + DNA

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5
Q

___ and ___ relax & stretch out to improve gene transcription.

A

Acetylated histones & methylated DNA

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6
Q

__ and __ of histones condenses chromatin.

A

Deacetylation & methylation

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7
Q

What is pre-mRNA?

A
  • precursor RNA

- altered within the nucleus to form mRNA

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8
Q

Alternative splicing

A

removal of introns (noncoding regions) & splicing of exons (coding regions)

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9
Q

What is mRNA and its fxn?

A
  • messenger RNA

- codes protein synthesis

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10
Q

What is tRNA and its fxn?

A
  • transfer RNA

- decodes mRNA

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11
Q

What is rRNA and its fxn?

A
  • ribosomal RNA
  • forms part of the structure of ribosomes
  • located in nucleolus
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12
Q

What are the 5 stages of Protein Synthesis?

A
  1. Activation of AA
  2. Initiation
  3. Elongation
  4. Termination & release
  5. Folding & post-translational processing
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13
Q
  1. Activation of AAs
A
  1. Carboxylation of the carboxyl group of each AA for the peptide bond formation
  2. Attachment of the AA to the tRNA in the cytosol by aminoacyl-tRNA synthetases
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14
Q
  1. Initiation
A
  1. mRNA binds to the small ribosomal subunit & to the aminoacyl-tRNA
  2. Large ribosomal subunit then binds to form the initiation complex
  3. The process is promoted by proteins called initiation factors (IF1, IF2, IF3)
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15
Q
  1. Elongation
A
  1. Polypeptide grows in successive attachment of AAs
    - Elongation requires cytosolic proteins (elongation factors) & GTP (creates peptide bond)
  2. Anticodons of tRNA binds to the codons of mRNA as the mRNA moves through the ribosome
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16
Q
  1. Termination & release
A
  1. A termination codon in the mRNA signals the completion of the polypeptide chain
  2. The new polypeptide is released in the cytosol with the help of release factors & GTP
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17
Q

What is a polyribosome?

A

mRNA + ribosomes (needed for translation)

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18
Q
  1. Folding & Post-translational processing
A
  • Folding into a 3D conformation helps polypeptide achieve its active form
  • Post-translational mods. may occur, including attachment of prosthetic groups (chemical tags, methylation, phosphorylation, etc.)
  • Formation of disulfide cross-links between cysteine residues protect the protein from denaturation in an extracellular environment
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19
Q

What is the role of a chaperone?

A

To help the polypeptide fold into its correct structure (Hsp60 & Hsp70)
- also help in polypeptide chains coming together to form quaternary structure

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20
Q

What does Ubiquitin bind to?

A

To one or more lysine residues in the target protein to be degraded by the proteasome complex to eliminate defective proteins

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21
Q

What is the major degradation route for regulatory proteins in the cytoplasm?

A

the ubiquitin-proteasome system

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22
Q

T or F: During cell division, each strand of the DNA acts as a template for the formation of a new complementary strand.

A

True

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23
Q

Organs grow & repair through what?

A

Mitosis

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24
Q

Gamates contain only half the # of chromosome as their parents cell and are formed by …

A

Meiosis

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25
Q

DNA helicases break what?

A

H-bonds between bases to produce 2 free strands

26
Q

DNA polymerases join what together?

A

Nucleotides together to form a complementary to the 1st DNA (semiconservative)

27
Q

The epidermis of the skin renews approx. every

A

2 weeks

28
Q

The stomach lining is renewed every …

A

2-3 days

29
Q

T or F: Striated muscle cells divide

A

False

30
Q

What is the interphase and what are they subdivided into?

A

The nondividing cell; G1, S, & G2

31
Q

What are Cyclins?

A

accumulate prior to mitosis and they promote different phases of the cell cycle

32
Q

During the G1 phase, what protein increases in its concentration and activates cyclin-dependent kinases to drive the G1/S phase transition?

A

Cyclin D

33
Q

Mutations may occur by …

A

errors during DNA replication

34
Q

What are oncogenes?

A

Genes that contribute to cancer

35
Q

What are proto-oncogenes?

A

Code for proteins that control cell division & apoptosis

36
Q

What is p53?

A

An important tumor gene suppressor (transcription factor)

  • Can help repair DNA or promote apoptosis so damaged cell cannot reproduce
  • Protects against damage caused by radiation, toxic chemicals, & cellular stress
37
Q

What is Mdm2?

A

proto-oncogene that is overexpressed in approx. 7% of cancers

  • Binds to p53 to transport it out of the nucleus & marks it for degradation
  • Mdm2 plays a role in tumorigenesis with or without p53
38
Q

What is necrosis?

A
  • Cell deprived of blood supply may swell, rupture their membranes, & burst
  • Cell membrane ruptures as terminal event & cell contents are released
  • Chemotactic factors lead to neutrophil infiltration to degrade dead cells
  • Lead to inflammatory response
39
Q

What is apoptosis?

A
  • Cells shrink, membranes remain intact but become bubbled
  • Blebs form apoptotic bodies containing nuclear fragments
  • Phagocytosis of intact apoptotic bodies
  • NO inflammatory response
40
Q

What are some reasons for apoptosis in pathologic conditions?

A
  1. DNA damage due to radiation and chemotherapy
  2. Accumulation of misfolded proteins leads to ER stress & apoptosis
  3. Viral infections
  4. Organ atrophy after duct obstruction
41
Q

What phases are in the interphase?

A

G1, S, & G2

42
Q

In Mitosis, 2 daughter cells receive the same what are the parents?

A

Same # of chromosomes

43
Q

At the end of the G2 phase, each chromosome consists of what?

A

2 strands called chromatids that are joined together by a centromere

44
Q

In Mitosis, each chromatid contains a complete what?

A

double helix DNA molecule

45
Q

Prophase

A

chromosome become visible as distinctive structures

46
Q

Metaphase

A

chromosomes line up along the equatorial plate of the cell

- Spindle fibers attach to the kinetochore at the centromere of each chromosome

47
Q

Anaphase

A

Centromeres split apart & the spindle fibers shorten, pulling the 2 chromatids in each chromosome to opposite pole

48
Q

Telophase

A

division of the cytoplasm, resulting in 2 identical daughter cells

49
Q

What is the function of a telomere?

A

Serve as caps on the ends of DNA, preventing enzymes from mistaking the normal ends for broken DNA and doing damage by “trying to repair them”

50
Q

What are telomerases?

A

Also called terminal transferase adds a telomere repeat sequence to the 3’ end of telomeres, duplicating the telomere DNA

51
Q

Stem cells than can divide indefinitely have what?

A

Telomerases

52
Q

In Meiosis, a diploid parent cell gives rise to what type of daughter cells?

A

haploid daughter cells

53
Q

How many sequences of cell division is required for the production of gamates

A

2

54
Q

In Meiosis, how many homologous pairs of autosomal chromosomes are there?

A

22

55
Q

In Meiosis, how many pair of sex chromosomes are there? (X and Y)

A

1 pair

56
Q

What gender has two X chromosomes?

A

Females

57
Q

What gender has one X and one Y chromosome?

A

Males

58
Q

At the end of Meiosis, each daughter cells contains how many chromosomes?

A

23 chromosomes and each consists of 2 chromatids

59
Q

How many daughter cells will result from meiosis of 1 parent cell?

A

4 daughter cells

- One out of the four cells progresses to become a mature ovum

60
Q

In what phase of meiosis does crossing over take place?

A

Prophase 1

Anatomy (5 decks)

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