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Anatomy & Physiology I > Chp 3, Part 3, Nucleus & Cell Cycle > Flashcards

Chp 3, Part 3, Nucleus & Cell Cycle Flashcards

1
Q

nucleus

A

-control center of the cell, containing genes for protein synethsis of most proteins (and dictates kind and amount of proteins)
-consists of nucleur envelope, nucleoli, and chromatin
-largest organelle
-cells can by multinucleate (like muscle, bone-destruction, or liver cells)
-mature red blood cells are anucleate (no nucleus)
-

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2
Q

nuclear envelope

A
  • selectively permeable, double membrane barrier separated by a fluid-filled space.
  • the outer membrane is continuous with the rough ER and also has ribosomes
  • inner membrane is lined by the nuclear lamina
  • has nucleus pores, which is lined by proteins forming an aqueous channel, regulating entry/exit of molecules (like mRNA)
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3
Q

nucleoli

A
  • AKA ‘little nuclei’
  • these are where ribosomal subunits are assembled and rRNA is synthesized. Then subunit+rRNA leaves through pore into cytoplasm where subunits form to make functional ribosome
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4
Q

Chromatin

A
  • bumpy weaved threads in nucleoplasm made of DNA, histone proteins, and RNA (newly formed/being formed) in un-condensed form
  • fundamental unit of chromatin = nucleosome (small length of DNA wrapped around histones)
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5
Q

chromosome

A
  • condensed chromatin, formed when a cell is preparing to divide.
  • prevent the delicate chromatin strands from tangling/breaking during the movements of cell division
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6
Q

nucleosome

A
  • unit of chromatin
  • made of 8 histone proteins connected like beads on a string. The DNA winds around the histones (packing the very long DNA molecules in more compact way)
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7
Q

Cell Cycle

A
  • series of changes a cell undergoes from the time it is formed until it reproduces
  • two major periods are interphase and mitosis (cell division)
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7
Q

Cell Cycle

A
  • series of changes a cell undergoes from the time it is formed until it reproduces
  • two major periods are interphase and mitosis (cell division)
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8
Q

Interphase

A
  • This is the metabolic/growth phase
  • split into G1, S, and G2 - during all three phases there is some growth (with most in G1) and DNA replication is in S phase (Synthetic)
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9
Q

mitosis / mitotic phase

A
  • where cell division occurs
  • split into Mitosis and Cytokinesis
  • Mitosis has 4 phases within it: Prophase, Metaphase, Anaphase, and Telophase (PMAT)
  • Produces (2) identical daughter cells - this is the process all human cells other than sex cells go through for division
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10
Q

Replication bubble

A

Active area of DNA replication

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11
Q

Replication fork

A

Point at which the DNA double helix unwinds for replication.

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12
Q

DNA polymerase

A
  • Enzyme that attaches to the template DNA strand and positions complementary nucleotides during DNA replication
  • synthesizes both new strands at one time (leading and lagging strand)
  • DNA Polymerase only works in one direction (3 to 5 prime direction), so the lagging strand ends up being discontinuous since it’s built backwards
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13
Q

DNA Ligase

A

Enzyme that splices short segments of discontinuous lagging DNA strand together

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14
Q

semiconservative replication

A

-The process of DNA replication since each daughter double stranded DNA contains one strand from the parent DNA and one new strand

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15
Q

Early Prophase

A
  • first phase of Mitosis
  • Chromatin condenses forming visible chromosomes (which is in duplicated sister chromatid form)
  • mitotic spindle starts to form from the centrosome
  • nucleoli disappears
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16
Q

Late Prophase

A
  • Nuclear envelope breaks up
  • kinetochore microtobules connect to the kinetochore of the chromosome center
  • nonkinetochore microtubles push against each other causing poles of cell to move farther apart
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17
Q

Metaphase

A
  • the chromosomes line up in center at spindle equator/metaphase plate
  • the centrosomes are at opposite ends of the cell
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18
Q

Anaphase

A
  • Shortest of all phases
  • centromeres of chromosomes split simultaneously becoming separate chromosomes and move away from each other
  • pulled to poles by kinetochores
  • nonkinetochore microtubules continue to push poles apart
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19
Q

Telophase

A
  • Starts when chromosome movement stops
  • each set of chromosomes (at opposite ends of cell) uncoil to resume chromatin form
  • new nuclear membrane forms around chromatin
  • nucleoli reappears
  • mitotic spindle disappears
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20
Q

Cytokinesis

A
  • Begins in late Anaphase and continues past Telophase

- actin microfilaments forms the cleavage furrow and physically pinches the cell apart

21
Q

nitrogen bases of DNA

A

Adenine - Thymine

guanine - cytosine

22
Q

Central Dogma

A

Process by which DNA genes are converted to a functional product (protein)

23
Q

Exon

A

-part of the gene that codes for amino acids

24
Q

introns

A

-non-coding segments interspersed among exons

25
Q

DNA

A

deoxyribose nucleic acid

double helix structure that contains code for all protein structure of our cells

26
Q

RNA

A
  • ribose nucleic acid
  • single stranded
  • carries out the decoding and messenger functions for protein synthesis
  • includes mRNA, rRNA, and tRNA
  • rather than Thymine, has the baes uracil (U)
27
Q

Messenger RNA (mRNA)

A
  • RNA involved in transcription - process of copying the DNA template strand with complementary RNA bases = single mRNA strand
  • Then the mRNA goes into the cytoplasm
28
Q

Ribosomal RNA (rRNA)

A
  • part of a ribosome

- consists of two subunits, which forms a ribosome where protein is synthesized

29
Q

pre-mRNA

A

mRNA before the introns are removed

30
Q

Transcription

A

process of encoding DNA in mRNA

31
Q

Translation

A

process of mRNA decoding to assemble polypeptides (which involves ribosome and tRNA)

32
Q

Transfer RNA (tRNA)

A
  • carrier of amino acid and an anticodon
  • the anticodon carries complementary base-pair with the codon of mRNA, adding the amino acid to growing polypeptide chain at the ribosome
33
Q

codon

A

3-base sequence of mRNA

34
Q

anticodon

A

on the end of tRNA contains the complementary three-base sequence to the mRNA codon

35
Q

ribosome binding sites

A

There’s an A site, P site, and E site.
-With a tRNA in the middle P site, a tRNA comes to the A site.
-the growing polypeptide chain in the P site is transferred to the amino acid carried in the A site
-the ribosome translocates, shifting each codon position along one, so that the ‘empty’ tRNA is now in the E/exist site, and the tRNA with the polypeptide chain is in the center, P site.
The process continues until a stop codon is reached in the A site.

36
Q

role of ER in protein synthesis

A
  • a SRP (signal-recognition particle) on the ER directs the mRNA-ribosome complex where to dock
  • once docked, the polypeptide chain enters the ER and sugar groups are added and overall shape changes
  • protein is enclosed in a vesicle for transport to Golgi Aparatus
37
Q

microRNA (miRNA)

A

a protective mechanism of a cell.

small RNAs that bind to and silence mRNAs made by certain exons.

38
Q

Riboswitches

A

-Folded RNAs that act as on/off switches for protein synthesis in response to environmental conditions

39
Q

Small Interfering RNAs (siRNA)

A

-can silence some mRNA exons from pathogenic sources

40
Q

autophagy

A
  • self eating.
  • the process of disposing of nonfunctional organelles and sweeping up cytoplasm bits by forming autophages, which are then degraded by lysosomes
41
Q

apoptosis

A
  • programmed cell death
  • process starts with mitochondrial membranes leaking chemicals that activate caspases enzyme
  • caspases enzyme cause degradation of DNA and cytoskeleton, leading to cell death
  • dead cell shrinks and is phagocytized by macrophages
42
Q

hyperplasia

A

accelerated growth that increases cell numbers when needed

43
Q

atrophy

A

decrease in size that results form loss of stimulation/use

44
Q

Genetic Theory of Cell Aging

A
  • end of mitosis and cell aging are programmed into genes
  • Telomeres (nucleotides that protect ends of chromosomes) shorten which each cell division, so acting like an hour-glass of cell
  • Telomerase is enzyme that lengthens telomeres but is absent in adult cells (only present in embryos OR cancer cells)
45
Q

Progeria

A

disease that mimics aging caused by defective progerin protein in nuclear lamina that causes unstable, abnormal nucleus

46
Q

Meiosis

A
  • process of cell division for germ cells in humans (sperm and eggs)
  • results in 4 haploid cells with only half of the DNA material as parent cell
  • goes through 2 rounds of cell division
  • daughter cells are not identical due to synapsis and crossing over
47
Q

cell differentiation

A
  • all cells in the body have the same genes but differentiate by active DNA (which then determines proteins) and chemical changes during embryonic stage.
  • leads to different structure and function
48
Q

SRP

A

a signal recognition particle that guides the ribosome+mRNA+amino acids to a receptor on the rough ER where the polypeptide chain enters for processing

49
Q

kinesin

A

type of motor protein that moves the sister chromatids once they have separated in Anaphase to opposite poles of cell

50
Q

nuclear lamina

A

rod-shaped proteins that form filaments), which maintains shape of nucleus and acts as scaffold to organize DNA

Anatomy & Physiology I (7 decks)

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