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BIO 150 A&P I > Unit 2: Ch 4 (Genetics & Cellular Function) > Flashcards

Unit 2: Ch 4 (Genetics & Cellular Function) Flashcards

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1
Q

Alternative Splicing of mRNA*

A
  • Process during gene expression that allows a single gene to code for multiple proteins
    • Introns are removed (spliced) from the sequence by snRNPs
    • Exons then move out of the nucleus into the cytoplasm
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2
Q

Anaphase

A
  • 3rd phase of mitosis
  • Activation of an enzyme that cleaves the two sister chromatids from each other at the centromere
  • Each chromatid is now a separate, single-stranded daughter chromosome
  • Daughter cells are genetically identical
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3
Q

AUG Codon

A
  • The start codon
  • Code for methionine
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4
Q

Base Pairs*

A
  • DNA
    • A with T
    • C with G
  • RNA
    • A with U
    • C with G
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5
Q

Base Triplet

A
  • Sequence of 3 DNA nucleotides that stands for 1 amino acid
  • Note
    • The minimum code to symbolize 20 amino acid is 3 nucleotides per amino acid, which is also the case for DNA
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6
Q

Cell cycle

A
  • Interphase
    • G1
    • S
    • G2
  • Mitosis (M)
    • Prophase
    • Metaphase
    • Anaphase
    • Telophase
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7
Q

Reasons for Cell Division

A
  • Cells…
    • Grow large enough to have enough cytoplasm to distribute to their two daughter cells
    • Have replicated its DNA, so it can give each daughter cell a duplicate set of genes
    • Received an adequate supply of nutrients
    • Stimulated by growth factors
    • Have neighboring cells that died, opening up space to be occupied by new cells
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8
Q

Chaperone

A
  • As a new protein is assembled by a ribosome, it is often bound by an older protein called a chaperone
  • Guides the new protein in folding into the proper shape and helps to prevent improper associations between different proteins
  • Also called stress proteins or heat shock proteins because they’re produced in response to heat or other stress on a cell and help damaged proteins fold back into their corrective functional shapes
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9
Q

Checkpoints

  • Description
  • Checkpoint locations
A
  • Description
    • At specific checkpoints during the cell cycle, a cyclin binds to a cyclin-dependent kinases (Cdks) and activates a cascade of biochemical reactions that prepare a cell to move on to the next phase of the cycle
  • Checkpoint locations
    • G1
    • G2
    • Metaphase
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10
Q

Chromosome Identification*

A
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11
Q

Primary parts of a chromosome*

A
  • Kinetochore: Protein plaque where centromeres attach genetic material
  • Centromere: Links a pair of sister chromatids
  • Sister chromatids: DNA replication of a chromosome
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12
Q

Codon

A
  • A 3-base sequence in mRNA
    • When mRNA is produced, it carries a coded message based on DNA triplets
    • The genetic code is expressed in terms of codons
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13
Q

How can multiple codons represent the same amino acid?

A
  • Sometimes two or more codons represent the same amino acid
  • This is explained mathematically
    • Four symbols (N) taken three at a time (x) can be combined in Nx different ways
    • There are 43 = 64 possible codons available to represent the 20 amino acids
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14
Q

Contact inhibition

A
  • The cessation of cell division in response to contact with other cells
  • An absence of contact inhibition, leading to uncontrolled cell division, is one of the characteristics of cancer
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15
Q

Cytokinesis

A
  • When the cytoplasm is divided into two cells, and the new cells begin interphase
    • Cellular division; a cleavage furrow forms around the equator of the cell and the cell eventually pinches in two
    • Overlaps with Anaphase and Telophase phases
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16
Q

DNA structure*

  • Description
  • Components
A
  • Double helix (resembles a staircase)
  • Hydrogen bonds
  • Components
    • Nitrogen base
    • Deoxyribose
    • Phosphorous group
  • Notes
    • Each sidepiece is a backbone composed of phosphate groups alternating with the sugar deoxyribose
    • The steplike connections between the backbones are pairs of nitrogenous bases
    • The bases face the inside of the helix and hold the two backbones together with hydrogen bonds
    • Across from a purine on one backbone, there is a pyrimidine on the other
    • The pairing of each small, single-ringed pyrimidine with a large, double-ringed purine gives the DNA molecule its uniform 2 nm width
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17
Q

Exons & Introns

A
  • Exons
    • Portions of DNA required to make a protein
  • Introns
    • Unnecessary instructions
    • Junk material
18
Q

G-Zero Phase (G0)

A
  • Cells that “rest” or cease to divide for days, years, or the rest of one’s life
  • Cells continue to perform normal functions, but no longer prepare for cell division
  • An inability to stop cycling and enter G0 is characteristic of cancer cells
19
Q

Gap Phase 1 (G1)

A
  • Occurs before DNA synthesis
  • Determines whether conditions are favorable to begin the cell cycle
  • Doubles its organelles, and accumulates the materials needed to replicate its DNA
20
Q

Second Gap Phase (G2)

A
  • Occurs after DNA synthesis
  • Checks the fidelity of DNA replication and usually repairs any errors detected
  • Cells synthesize the proteins needed for cell division
21
Q

Gene Expression*

A

Taking DNA instructions and ending up with an outcome

22
Q

Genome

A
  • All genes of a specific organism
  • 23 chromosome sets in a human = 46 chromosomes
23
Q

Law of Complementary Base Pairing

A
  • The fact that one strand governs the base sequence of the other
  • It enables us to predict the base sequence of one strand if we know the sequence of the complementary strand
24
Q

Meiosis

A

Cell division mechanism that is restricted to the production of eggs and sperm

25
Q

Metaphase

A
  • 2nd phase of mitosis
  • The spindle fibers form a mitotic spindle
  • Shortend microtubles form a star-like aster, which anchors the assembly to the inside of the plasma membrane at each end of the cell
26
Q

Mitosis

  • Description
  • Functions
  • Phases
A
  • Description
    • Nuclear division
    • Cell division mechanism that serves all functions of cell division, except for the production of eggs and sperm
  • Functions
    • Development of an individual
    • Growth of all tissues and organs after birth
    • Replacement of cells that die
    • Repair of damaged cells
  • Phases
    • Prophase
    • Metaphase
    • Anaphase
    • Telophase
  • Note
    • Can occur without cytokinesis (cellular division) which is why some cells acquire two or more nuclei or multiple identical sets of chromosomes
27
Q

Nitrogenous Bases*

A
  • 1 purine bonds with 1 pyrimidine via H bond
  • Purines (2 ring structure)
    • Adenine (A)
    • Guanine (G)
  • Pyrimidines (1 ring structure)
    • Cytosine (C)
    • Thymine (T) - only in DNA
    • Uracil (U) - only in RNA
28
Q

Components of a Nucleotide

A
  • Sugar
  • Phosphate group
  • Single- or double-ringed nitrogenous base
29
Q

Nucleotide Chain Components in RNA & DNA*

A

RNA

  • Ribose
  • 1 of the following nitrogenous bases: U, C, G, A
  • Phosphate group

DNA

  • Deoxyribose
  • 1 of the following nitrogenous bases: T, C, G, A
  • Phosphate group
30
Q

Pre-mRNA

A
  • RNA produced by transcription is an “immature” form of RNA, called pre-mRNA
  • It contains segments:
    • Exons: Will be translated into a protein (exported from the nucleus to undergo translation in the cytoplasm)
    • Introns: Are removed before translation (removed while still in the nucleus)
31
Q

Prophase

A
  • 1st phase of mitosis
    • Nuclear envelope disintegrates and releases the chromosomes into the cytosol
    • Spindle fibers form
      • Centrioles begin to sprout elongated microtubules called spindle fibers, which push the centrioles apart as they grow
      • The spindle fibers then tug the chromosomes back and forth until they line up along the midline of the cell
32
Q

Proteome*

A

All the proteins found within an organism

33
Q

RNA Types*

A
  • Messenger RNA (mRNA)
    • Transcribes the genetic code from DNA into a form that can be read and used to make proteins
    • Carries genetic information from the nucleus to the cytoplasm of a cell
  • Ribosomal RNA (rRNA)
    • Located in the cytoplasm of a cell, where ribosomes are found
    • Directs the translation of mRNA into proteins
  • Transfer RNA (tRNA)
    • Located in the cellular cytoplasm and is involved in protein synthesis
    • Binds amino acids to the ribosome that corresponds to each three-nucleotide codon of rRNA
    • Amino acids then can be joined together and processed to make polypeptides and proteins
34
Q

Synthesis (S) Phase

A
  • DNA synthesis/replication
  • Makes a duplicate copy of its centrioles and nuclear DNA
  • At the end of the stage, each chromosome consists of two sister chromatids that have identical DNA sequences which remain attached until they are separated during mitosis
35
Q

Stop Codons

A
  • UAG, UGA, and UAA
  • They signal “end of message” like a period at the end of a sentence
  • Enables the cell’s protein-synthesizing machinery to sense that it has reached the end of the instruction for a particular protein
36
Q

Telophase

A
  • 4th phase of mitosis
    • Rough ER produces a new nuclear envelope around each cluster, and the chromosomes begin to uncoil and return to the thinly dispersed chromatin form
    • Daughter chromosomes cluster on each end of the cell
  • Telophase is the end of nuclear division but may overlap with cytokinesis
37
Q

Transcription stages

A
  • Initiation
    • RNA polymerase binds to a sequence of DNA called the promoter (start codons), found near the beginning of a gene
    • RNA polymerase separates the DNA strands, providing the single-stranded template needed for transcription
  • Elongation
    • One strand of DNA acts as a template for RNA polymerase
    • As it “reads” this template one base at a time, the polymerase builds an RNA molecule out of complementary nucleotides
  • Termination
    • Sequences called terminators (stop codons) signal that the RNA transcript is complete
    • Once they are transcribed, they cause the transcript to be released from the RNA polymerase
38
Q

Transcription*

  • Description
  • List of stages
A
  • The 1st step in gene expression
    • DNA → mRNA → Protein
      • Purpose is to make RNA copies of individual genes
      • Performed by RNA polymerases, which link nucleotides to form an RNA strand
      • Produces mRNA, tRNA, rRNA, and non-coding RNA
      • Occurs in the nucleus
  • Ends when RNA transcript is released and polymerase detaches from DNA. DNA rewinds itself into a double-helix and is unaltered throughout this process
  • Note
    • → = Codes for the production of
39
Q

Translation stages

A
  • Initiation
    • Ribosome joins with the mRNA and the first tRNA so translation can begin
  • Elongation
    • Amino acids are brought to the ribosome by tRNAs and linked together to form a chain
  • Termination
    • The finished polypeptide is released to perform its action in the cell
40
Q

Translation*

A
  • 2nd step of gene expression
    • DNA → mRNA → Protein
      • Protein synthesis from an mRNA template
      • Uses rRNA as an assembly plant, and tRNA as the translator to produce a protein
      • Occurs in the cytoplasm
      • Ends when the ribosome encounters one of the three stop codons; disassembles the ribosome and releases the polypeptide
  • Converts the language of nucleotides into the language of amino acids
  • Synthesized protein will then:
    • Stay in cell & become an instruction for that cell
    • Attach to cell membrane & function as a protein
    • Leave cell to provide instruction to a different cell
  • Note
    • → = Codes for the production of

BIO 150 A&P I (25 decks)

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