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cell biology > 101 cell bio > Flashcards

101 cell bio Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are the three types of cytoskeletal filaments

A

MICROFILAMENTS [actin]
MICROTUBULES [tubulin]
INTERMEDIATE FILAMENTS

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2
Q

describe microfilaments

A
  • smallest filament [actin]
  • directly below plasma membrane
  • dynamic, flexible structures that enable cells to adapt specialised shapes [microvilli, stereocilia, contractile structures]
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3
Q

what is myosin

A

MOTOR PROTEIN that travels along microfilaments [actin]
- causes cell contraction and movement
- bundle together to create protein heads = creating thick filament in sarcomeres [muscle tissue]
- attaching, powerstroking, releasing + cocking

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4
Q

describe microtubules

A

more rigid than MF
- plays a role in cilia and flagella movement
- forms spindles in cell division
- long, straight and hollow structures
- acts as a track for motor proteins [kinesin and dynein]

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5
Q

what is kinesin

A

MOTOR PROTEIN that travels to the positive end of a MT
- vesicle and organ support

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6
Q

what is dynein

A

MOTOR PROTEIN that moves toward negative end of a MT
- projections with a rhythmic beating motion
- for flagella and motile cilia
- core of flagella formed from an AZONEME; 9 sets of doubled MT

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7
Q

intermediate filaments

A

STABLE length, diverse composition
- provide strength and support
- lacks polarity, lattice appearance
- keratin, vimentin and lamin
- IF made from KERATIN are important for internal support, help anchor skin cells to ECM and adjacent cells
- cells without IF are easily damaged

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8
Q

4 types of DNA mutations

A

missense
silent
frame shift
non-sense

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9
Q

missense mutation

A

substitution
- changes amino acid formed

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10
Q

silent mutation

A

substitution
- does NOT change amino acid formed

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11
Q

non-sense

A

premature stop codon appears

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12
Q

frame shift

A

deletion or insertion of a nucleotide
- alters downstream pattern

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13
Q

what is a phospholipid

A

forms the semi-permeable lipid bilayer
- hydrophobic tail [made from two fatty aids; one is saturated, the other unsaturated]
- hydrophilic head

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14
Q

describe selectively permeable

A

-non-polar molecules diffuse readily through the membrane [lipid soluble molecules]. also SMALL polar molecules
- larger polar molecules [+ ions with an electrostatic charge] may not be able to. some may need assisted transport

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15
Q

simple diffusion

A

passively and freely moving through bilayer
- net movement WITH the concentration gradient
-O2, CO2

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16
Q

facilitated diffusion

A

passive movement down the concentration gradient
- assisted by channels and carriers
- larger molecules and ions

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17
Q

describe some roles of proteins

A
  • transporter: allow physical relocation of substances
  • receptor: transmit signals, transduce incoming signals
  • enzyme
  • anchor: do not move freely in membrane, bound to other cellular components
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18
Q

hypotonic solution

A

causes cells to swell and burst
[cytolysis]

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19
Q

hypertonic solution

A

causes cells to shrivel/shrink
[plasmolysis]

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20
Q

isotonic solution

A

solution is normal. no change to cell

21
Q

the 6 phases in cell division

A
  • interphase [not usually included
  • prophase
  • metaphase
  • anaphase
  • telophase [+ cytokinesis]
22
Q

describe mitosis

A

cell division that produces identical daughter cells [2]
- occurs in somatic cells
- same no. chromosomes as the parent
- important for growth and regeneration

23
Q

describe meiosis

A

cell division utilised in sexual reproduction
- four genetically different daughter cells
- forms gametes of the body
- PMAT x2
- meiosis in males = sperm. meiosis in females = eggs

24
Q

interphase

A

a precursor to both meiosis and mitosis
- DNA replication
- still has 46 chromosomes, however now has 92 chromatids
- growth and conducting normal cell functions

25
Q

what is crossing over

A

transfer of genetic information between homologous pairs
- occurs in prophase I

26
Q

differences between DNA and RNA

A

RNA is single stranded, less stable, much shorter, does not form a double helix, more prone to error because it utilises UAGC.
DNA is doubled stranded and forms a double helix, is longer, more stable and uses TAGC

27
Q

types of RNA

A

Messenger RNA: encodes proteins and protein synthesis
ribosomal RNA: protein synthesis
transfer RNA: protein synthesis
Small nuclear RNA: gene regulation and binding with proteins to form spliceosome

28
Q

transcription

A

synthesis of RNA from a DNA template

29
Q

translation

A

synthesis of a protein from an mRNA template
- converted into an amino acid sequence in a protein.

30
Q

how does pre-mRNA become mRNA

A

pre-mRNA is formed from DNA entering the polymerase and splitting temporarily.
- pre-mRNA is spliced: removing the introns. EXONS must stay, as they contain codons
- 5’ cap is added [start; needed for translation; support and stability]
- 3’ cap [prevents degradation]
- exported from nucleus as mRNA

31
Q

types of transcription factors that bind to DNA

A

1) general transcription factors
2) sequence specific transcription factors

32
Q

what are the generalised transcription factors

A
  • DNA has a TATA box, promoter and terminator sequence
  • transcription begins in the TATA box, does not stop until it reaches terminator sequence
  • expressed by all cells
  • same factors for all genes
33
Q

what is a promoter

A

at the start of a DNA sequence, contains the TATA box

34
Q

initiation of transcription

A

when the TATA binding protein [TBP] binds to the TATA box.
- RNA polymerase attaches to transcription site and begins to move along DNA, creating the RNA
- Other general transcription factors are also recruited to form transcription initiation complex

35
Q

describe sequence-specific transcription factors

A

bind to ENHANCERS that can either promote or hinder recruitment of transcription machinery
- can be upstream or downstream
- different enhancers = different genes and different factors
- different cells = different factors

36
Q

what is signal transduction

A

converting extracellular signals into intracellular signals
- hormones, nutrients, neurotransmitters, mechanical stimuli, ECM
signal = receptor = intracellular signaling proteins = effector proteins = cell response

37
Q

describe the two types of close range signaling

A

autocrine signaling - cell produces the signal that it responds to
paracrine signaling - signal produced by one cell, responded by another

38
Q

describe long range endocrine singaling

A

second messengers
- travel through bloodstream
- small and diffusible molecules/ions that relay signals inside the cell
- physically interact with- and activate- downstream signaling proteins

39
Q

three major classifications of cell surface receptors

A

1) ion channel coupled receptors
2) enzyme-coupled receptors
3) g-protein coupled receptors

40
Q

ion channel coupled receptors

A

found at the SYNAPSE
- important for neuron signaling
- regulate entry of Ca2+, K+ and Na+ ions

41
Q

enzyme coupled receptors

A

receptor that has enzymatic activity, or direct association with an enzyme
- ligand binding activates enzyme activity

42
Q

g-protein coupled receptors

A

“molecular switch”
dissociates from subunits, alpha binds to ATP and activates second messengers

43
Q

what are ribosomes composed of

A

proteins and ribosomal rna [rRNA]
- it has three binding sites for tRNA [E, P, an A]

44
Q

What is transfer RNA

A

an adapter between amino acids and mRNA
- anticodon loop binds to mRNA, base pairing. forms amino acid

45
Q

overview of translation

A
  • polypeptide chain forms off of tRNA in P position
  • incoming tRNA with new AA binds to the A position
  • tRNA moves from A site to P site, AA joins chain
  • the tRNA from the P site moves to the E site, and thereafter leaves
  • continues until the STOP codon, where the ribosome subunits dissociate
46
Q

difference between protein synthesis [locations]

A
  • nuclear, mitochondrial and cytoplasmic proteins complete translation on free cytoplasmic ribosomes
  • membrane-bound and secreted proteins move to the rER membrane to complete protein synthesis
47
Q

what causes the ribosome to move to the rough endoplasmic reticulum

A

signal sequencing
1. signal sequence translated
2. binds to a signal recognition particle [SRP] and translation pauses
3. SRP binds to receptor on rER membrane
4. signal sequence binds to translocator on rER membrane and translation continues
5. signal sequence removed
6. polypeptide in rER lumen

48
Q

how does a protein move to the cell surface

A

ER-Golgi trafficking
- transport system involving vesicles
- secretory vesicles leave golgi and transport protein to the cell surface [via exocytosis]

cell biology (1 decks)

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