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A & P1 for PCP > Lecture 2 Cells, DNA, mol > Flashcards

Lecture 2 Cells, DNA, mol Flashcards

1
Q

the cell is

A

the basic organizational structure of human body

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2
Q

how many cells in body

A

50 - 100 trillion

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3
Q

differentiation is:

A

when cells specialize

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4
Q

cells vary in :

A

size
shape
function

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5
Q

what is a composite cell and its 4 major parts

A

a typical cell

  1. nucleus
  2. cytoplasm
  3. cell membrane
  4. organelles
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6
Q

what is function of cell/plasma membrane

A
  • actively participates in cell metabolism

- barrier btw in & out of cell

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7
Q

what is structure of cell membrane

A
  • dbl layer of phospholipids interconnected with other lipids (ex. cholestrol = helps stabilize membrane by reducing phospholipid mobility)
  • proteins in membrane can be trans-membrane= integral/integrated or peripheral (on surface)
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8
Q

what is electrochemical gradient

A
  1. ELECTRO = charge -/+ inside vs outside of cell, dictates where ions want to go
  2. CHEMICAL = concentration inside vs outside of cell dictates where mol wants to go
    - this is when those two forces move molecules across membrane
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9
Q

proteins in cell membrane function as these 4 things

A
  • transporter
  • receptors - signals
  • cytoskeleton anchors
  • enzyme activity
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10
Q

what is cytoplasm

A

thick solution that fills cell inside plasma membrane

  • Cytosol = water
  • organelles = solids
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11
Q

what is mitochondria

A

powerhouse of cell

-generates ATP for cell to use as energy

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12
Q

what is endoplasm reticulum

A
  • area of protein synthesis
  • lipid synthesis
  • calcium storage and release
  • smooth or rough ER
  • rough ER has ribosomes on outer layer to create proteins
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13
Q

what are ribosomes

A
  • made of RNA (make proteins then send to rough ER)
  • site of protein synthesis
  • on outside of rough ER
  • uses mRNA to determine order of amino acids to create given protein
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14
Q

what is golgi apparatus

A
  • process and package proteins and lipids in vesicles
  • vesicles usually go to reach cell membrane and help expulsion of the proteins/ lipids outside the cell (preps proteins & lipids to send out of cell
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15
Q

what are centrioles

A
  • tube like things near center of cell

- assist in cell division

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16
Q

what are microtubules

A
  • major component cytoskeleton

- cellular mobility, intracellular transport, maintaing cell shape and structure.

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17
Q

What are microfilaments

A
  • major component of the cytoskeleton

- coordinate contraction and transport of vesicles

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18
Q

What are cilia

A

Short hair like projections

- propel substances on cell surface

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19
Q

What are flagellum

A
  • long tail like projections

- provide motility to sperm

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20
Q

What are Microvili

A
  • tiny protrusions of the cell membrane
  • increase absorption
    Ex. Intestine
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21
Q

What is cell nucleus

A

Control center of the cell

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22
Q

What is nuclear envelope

A
  • porous double membrane

- separates nucleoplasm from cytoplasm

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23
Q

What is nucleolus

A
  • dense collection of RNA and proteins

- site of ribosome production

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24
Q

What is chromatin

A
  • fibers of DNA and proteins

- stores info for synthesis of proteins

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25
Q

What is passive cellular transport and 4 types

A

Requires no energy

  • simple diffusion
  • facilitated diffusion
  • osmosis
  • filtration
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26
Q

What is active cellular transport and 4 types

A

Requires cellular energy

  • active transport
  • endocytosis
  • exocytosis
  • transcytosis
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27
Q

What is simple diffusion

A
  • movement of substances from regions of higher concentration to regions of lower concentration.
  • oxygen, carbon dioxide and lipid-soluble substances
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28
Q

What is facilitate diffusion

A
  • diffusion across a membrane with the help of a channel or carrier molecule
  • ex. Glucose and amino acids
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29
Q

What is osmosis

A
  • movement of water through selectively permeable membrane from region higher concentration to region of lower concentration.
  • water movement toward a higher concentration of solutes.
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30
Q

What is osmotic pressure

A

Ability of osmosis to generate enough pressure to move a volume of water
- increases as the concentration of non permeable solutes increases.

31
Q

What is isotonic solution

A

Cells retain their normal size and shape as same solution/water concentration inside and outside of cell.

32
Q

What is a hypertonic solution

A

Higher osmotic pressure (water loss)

33
Q

What is Hypotonic solution

A

Lower osmotic pressure ( water gain)

34
Q

What is filtration

A
  • smaller molecules are forced through porus membrane
  • hydrostatic pressure is important in the body
  • molecules leaving blood capillaries
35
Q

What is active transport

A
  • carrier molecules transport substances across a membrane from regions of lower concentration to regions of higher concentration utilizing ATP (energy) to do so
  • ex. Sugars, amino acids, sodium ions, potassium ions, etc..
36
Q

What is sodium-potassium pump

A

Creates balance by pumping 3 sodium (Na+) out and 2 potassium (K+ ) into the cell.
-3:2 ratio

37
Q

What is secondary active transport

A
  • uses the energy stored in a concentration gradient
  • the gradient is established through active transport.
  • symporters move substances in the same direction
  • antiorters move substances in opposite directions
38
Q

What is endocytosis

A
  • cele engulfs a substance by forming a vesicle around the substance
  • net movement is into the cell
39
Q

What are the 3 types of endocytosis

A
  1. Phagocytosis: substance is a solid. Produce phagosome (endocytotic vesicle) which combines with a lysosome
  2. pinocytosis: substance is mostly water. Produce vesicle
  3. Receptor-mediated endocytosis: requires the substance to bind to a membrane-bound receptor.
40
Q

What is exocytosis

A
  • Reverse of endocytosis
  • substances in a vesicle fuse with cell membrane
  • contents released outside the cell
  • ex. Release of neurotransmitters from nerve cells
41
Q

What is transcytosis

A
  • endocytosis followed by exocytosis
  • transports a substance rapidly through a cell
  • HIV crossing a cell layer
42
Q

What is DNA

A

Deoxyribonucleic acid

  • double helix or 2 complementary strands
  • Guanine, cytosine, adenine, thymine
43
Q

What is RNA

A

Ribonucleic acid

  • simple strand
  • guanine, cytosine, adenine, uracil
44
Q

Who were the first to publish a model of DNA structure

A

In 50’s Watson & Crick

45
Q

A nucleotide is made up of:

A 
1 phosphate group
1 sugar (deoxyribose=DNA, ribose=RNA)
1 nucleobase (=nitrogen base)
46
Q

What are the obligatory base pairs of DNA

A

Adenine and thymine

Cytosine and guanine

47
Q

What are the 2 processes of protein synthesis

A
  1. Transcrption: copying of the DNA code to a RNA strand
  2. Translation: taking the RNA code and reading it to transfer the information into a protein.

DNA -> RNA -> protein

48
Q

What happens in transcription

A
  • many enzymes are involves
  • the 4 nucleotides dont differ structure, it’s their sequence that makes them unique
  • the enzyme DNA polymerase causes the helix to unwind
  • Nucleobases of RNA bind to the exposed DNA nucleotides to form mRNA
  • mRNA that has undergone transcription is then modified in the nucleus by removing certain segment (INTRONS= non info regions) and then the remaining segments (EXONS= coding regions) are joined (spliced)
  • lastly mRNA exits the nucleus and goes into the cytoplasm where the TRANSLATION will occur by the ribosomes to obtain protein
49
Q

What else does DNA code for in transcription

A
  • rRNA: joins with the ribosomal proteins to give rise to the ribosomes
  • tRNA: searches and adds the appropriate codons to mRNA
  • one codon (3 RNA base pairs) coded for a single amino acid
50
Q

What happens in Translation

A
  • mRNA joins 2 ribosome subunits and becomes sandwiched btw them
  • protein synthesis begins at the codon AUG on the mRNA
  • A tRNA with the matching anti-codon and amino acid will enter the A site of the ribosome
  • tRNA will form h-bonds with mRNA
  • at site P the peptide bonds are formed btw the amino acids
  • at site E the tRNA is released without the amino acid
  • this continues until the Stop Codon (UGA, UAA, UAG)
  • the polypeptide chain detaches & if there is not another mRNA, the 2 subunits of the ribosome seperate.
  • many ribosomes line up to translate the same mRNA in multiple copies of the same protein
51
Q

Where do the newly created proteins go once produced by ribosomes

A

Into the cytoplasm

  • all cells of an organism contain the same genetic package , but not all Gene’s are expressed in all cells
  • each type of cell produces proteins necessary for it’s own functions and locations in the organism
52
Q

What are two types of proteins that are created by ribosomes but then sent directly out of cell and only activates when it get to specific site

A
  1. Trypsin: pancreatic enzyme that’s secreted as trypsinogen in small intestine
  2. Enteropeptidase: (enterokinase) enzyme present in small intestine that activate the trypsinogen to trypsin
    - tripsin digests proteins (dont want it to function until in small intestine)
53
Q

What is an overview of basic cell cycle 4 phases

A

G1 - Growth 1 (cells that do not reproduce stop here)
S - growth and DNA synthesis
G2 - growth and final preparation for division
- those 3 fall under Interphase

M - Mitotic phase

54
Q

What are the 2 types of cell division

A

Somatic (mitosis) = diploid (2n) = 46 (23 pairs) chromosomes -> to repair and replace

Reproductive (meiosis) = haploid (n)= 23 chromosomes -> reproduction

55
Q

What is Interphase

A
  • where cell spends most time doing norm function
  • at start chromosomes are not condensed but form filamentous mass of chromatin
  • chromosomes will condense only for cell division; in this state it is formed of 2 chromatids which are 2 copies of the same chromosome
  • chromatids are from DNA replication
  • when chromatin duplicates, each chromatids remain attached to its copy by the Centromere
  • if the cell will divide, DNA & the centrosomes will be be replicated in this phase
  • protein & RNA synthesis necessary for cell division is undertaken
  • there are 3 sub steps of interphase
56
Q

What happens in G1 phase

A
  • cell is occupied with its metabolic function and it’s own upkeep
  • cells that do not divinde (ex. Nervous & myocytes) remained blocked at G1 (called G0)
  • few cell activities are related to cell division here except near the end where centrioles replication occur
  • the length of time varies a lot (few minutes to a few days)
57
Q

What happens in S phase

A
  • here DNA is replicated
  • chromosomes replicate & are attached by their centromere & remain at this point in the form of chromatin
  • DNA replication cannot be cancelled at this point
  • each of the 2 DNA strands is read & a complementary copy is done; DNA-POLYMERASE is involved
58
Q

What happens during G2 phase

A
  • brief phase of growth
  • final prep for cell division (synthesis of certain necessary proteins & RNA)
  • this is very important bcs once prophase has begun (chromosomes condensed), mRNA synthesis is no longer possible.
59
Q

What are the 2 types of cell division

A
  1. Nuclear division:
    - mitosis (somatic)
    - meiosis (gametes)
  2. Cytoplasmic division:
    - cytokinesis
60
Q

What is end result of mitosis

A

1 mother cell divides into 2 identical daughter cells

61
Q

what are the 4 steps after interphase of mitosis

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
62
Q

Describe prophase of mitosis

A
  • Chromatin condenses into chromosomes
  • pair of chromatids are held by their Centromeres
  • nucleolus & nuclear envelope disappear
  • Centrioles: 1. migrate to opposite poles, 2. organize the mitotic spindle (microtubules)
63
Q

What are the 3 microtubules

A
  1. Polar: go beyond chromosomes & go towards opposite poles
  2. Kinetochore: these microtub. attach to the kinetochores (these attach to chromosomes)
  3. Aster: go in opposite direction of the mitotic spindle (anchors spindle to plasma membrane)
64
Q

What happens in metaphase of mitosis

A

Chromosomes align at the Equatorial plate

65
Q

What happens in Anaphase of mitosis

A
  • Centromere divide & each chromosome separate from its homologue
  • chromosomes migrate twrd the poles by shortening the kinetochore microtubules
  • chromosomes migrate in the form of a V & crosses all the cytoplasm
66
Q

What happens in Telophase of mitosis

A
  • chromosomes return to the state of chromatid
  • kinetochore microtubules disappear & polar microtubules elongate
  • mitotic spindle dissolves
  • nuclear envelope form again
  • 2 cells are almost divided
67
Q

What is cytokinesis

A

-the cells divide its cytoplasmic content in & becomes 2 cells

68
Q

What is meiosis

A
  • the cells divide to give 4 half cells
  • only done at the level of the ovaries & the testis to form gametes
  • interphase is the same as mitosis
69
Q

What happens in prophase 1 meiosis

A

Same plus synapsis occurs: homologous chromosomes come tgthr along their length to form tetrads
-during synapsis the arms of homologous chromatids wrap around each other = crossover (trading segments)

70
Q

What happens in metaphase 1 meiosis

A

the tetrads align randomly on the spindle equator in prep for anaphase

71
Q

What happens in anaphase 1 meiosis

A
  • centromeres DO NOT separate, so the sister chromatids (dyads) remain firmly attached.
  • the homologous chromosomes do separate from each other & the dyads move twrd opposite poles of the cell
72
Q

What happens in telophase 1 meiosis

A
  • nuclear membranes re-form around the chromosomal masses
  • spindle breaks down
  • chromatin reappears as telophase & cytokinesis end
  • the 2 daughter cells (now haploid) enter a second interphase-like period, called interkinesis before meiosis ii occurs (no 2nd replication of DNA)
73
Q

What happens in Meiosis II

A
  • Starts with product of meiosis I (2 haploid daughter cells)
  • undergoes mitosis-like nuclear division
  • end result is 4 haploid cells each diff than mother

A & P1 for PCP (19 decks)

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