Study Exercise Biology 20 - 24

8/10/2019 Study Exercise Biology 20 - 24

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Study exercise Biology 20 24

1. What are the major morphological differences between RERand SER?, Major differences in their function

Rough Endoplasmic Reticulum (RER) Smooth Endoplasmic Reticulum (SER)Membrane covered with Ribosomes Membrane not covered with Ribosomes

Found in cells which actively synthesize proteins

Found in cells which are involved in thesynthesis of non protein molecules steroids, phospholipids

produces two types of proteins; amino acidsand polypeptides from cytosol which is theinterstitial fluid of the cell.It produces protein to provide the substanceto secretory vesicles, Golgi bodies, plantvacuoles, endosomes, lysosomes, and foritself

functions in several metabolic processes synthesis of lipids and steroid

metabolism of carbohydrates regulation of calcium concentration drug deto!ification attachment of receptors on cell

membrane proteins steroid metabolism contains the enzyme glucose"#"

phosphatase which converts glucose"#"phosphate to glucose, a step ingluconeogenesis.

R$R can transfer the synthesized product, protein, to the Golgi bodies for furtherdevelopment from the location where the

protein will be distributed to its re%uiredsites but also regulates the product it

produces

&$R is the structure responsible for liberatingcalcium during the contraction of muscles.

has the ability to produce insulin in the caseof pancreatic cells for white blood cells orleu'ocytes as it is responsible for theformation of antibodies
http://www.differencebetween.net/science/health/difference-between-braxton-hicks-and-contraction/http://www.differencebetween.net/science/health/difference-between-braxton-hicks-and-contraction/http://www.differencebetween.net/science/health/difference-between-braxton-hicks-and-contraction/


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(he membrane of the R$R is continuouswith the outer layer of the nuclear envelope.)lthough there is no continuous membrane

between the R$R and the Golgi apparatus , membrane"bound vesicles shuttle proteins

between these two compartments. (he R$Rwor's in con*unction with the Golgi comple!to target new proteins to their properdestinations. ) second method of transportout of the $R are areas called membranecontact sites. +ere, membranes of the $Rand other organelles are held closelytogether, allowing the transfer of lipids andother small molecules.

(he &$R consists of tubules and vesicles that branch and form a networ'.In some cells there are dilated areas, li'e thesacs of R$R. (he networ' of &$R allowsincreased surface area for the action orstorage of 'ey enzymes and the products ofthese enzymes.

2. escribe the steps that occur as a soluble secretor! protein,such as a digesti"e en#!me in a pancreas cell, mo"es fromthe RER to the cis $olgi cisterna% from the cis cisterna to the&$' ( Vesicular transport isternal progression -anterograde directed forward in movement, reterograde

bac'wards/

o cis"Golgi cisterna 0cargo of protein 0 move form cis 0medial

0trans

(G1 -trans Golgi networ'/ proteins not transport to $R or Golgi, are

destined for compartment to others -by different types of vesicles/

o from trans 0fuses membrane 0trnasport 0e!ocytosis

o from trans 0stored inside 0formation of secretory

vesicles; release by signal for e!ocytosis

o from trans 0late endosome 0lysosome -intracellular degradation of organelle/

the mechanism not well 'now
https://www.boundless.com/biology/definition/golgi-apparatus/https://www.boundless.com/biology/definition/golgi-apparatus/https://www.boundless.com/biology/definition/golgi-apparatus/


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). escribe the mo"ement of materials b! "esicular transportbetween membranous compartment of thebios!nthetic*secretor! pathwa!. See +igure .2-

. escribe the three distinct roles of l!sosomes 2ysosomes serve as intracellular digestive system digestive bags.

(hey destroy any foreign material which enter the cell such as bacteria or virus.


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2ysosomes also remove the worn out and poorly

wor'ing cellular organelles by digesting them to ma'e

way for their new replacements scavengers, cellular

house'eepers or demolition s%uads.

2ysosomes form a 'ind of garbage disposal system of

cell 3uring brea'down of cell structure, when the cell gets

damaged, lysosomes burst and the enzymes eat up their

own cells suicide bags of a cell.

FU !"#$ S

%utophagy

o )utophagy is the intracellular process by which the cell degrades its own

components using the lysosomal machinery and recycles the molecules.

o 3amaged macromolecules, malformed proteins, non"functional, long"lived

proteins, and damaged and old organelles are all bro'en down by the

lysosomal enzymes.

o 4rocess

) phospholipid membrane is formed around the target component,

resulting in the formation of a vesicle called autophagic vacuole.

(his vacuole then fuses with the primary lysosome where thehydrolases digest the macromolecules to sugars, amino acids and

nucleotides, which are the primary building bloc's of every cell.

(hese useful digestion products are released into the cytosol and can

be utilized in the synthesis of new macromolecules and organelles,

whereas the unwanted products are released outside the cell. )lso,

during starvation, or nutrient"limiting conditions, autophagy of

normal organelles occurs, thus helping to maintain the level of

nutrients re%uired for the normal cellular processes.


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Role in Endocytosis and &hagocytosis

o $ndocytosis is the process for cellular upta'e of foreign material.

o 4hagocytosis is a specialized form of endocytosis wherein large bodies such

as dead cells, cell debris, bacteria, viruses, etc., are engulfed.

o (he upta'e occurs through specialized vesicles which fuse with the

lysosomes followed by the degradation of the foreign entity by hydrolases.

3irectly or indirectly, both these processes play a crucial role in pathogen

destruction.

Role in %poptosis


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o )poptosis or programmed cell death is a very intricately controlled

mechanism of cellular suicide.

o &uch a mechanism is essential during embryonic development and for

destruction of old cells, infected cells and cells with 31) damage.

o 4R5 $&&

initiated through various pathways in a cell, one of them being

lysosome"mediated apoptotic pathway

ertain proteases present in lysosomes have been identified as one of

the initiators for such cell death these proteases lead to a series of

signals and events characterized by brea'down of the cellular

components.

(hese components are pac'ed into vesicles termed apoptotic bodies

which are engulfed by neighboring cells. (he lysosomes of the

neighboring cells bring about the residual digestion of these

components.

Role in Fertili'ation

o 2ysosomes are also capable of releasing their digestive enzymes outside the

cell to bring about e!tracellular digestion.

o 3uring fertilization, the lysosomal contents of sperms are released outside

the cell in order to bring about the digestion of the limiting membrane around

the egg. facilitates fusion of the sperm and egg.

In addition to this, once the two cells fuse, the paternal mitochondria

are destroyed through the lysosomal machinery of the egg.

&perm"derived mitochondria tend to accumulate genetic mutations

due to the high metabolic activity of sperms they need to be

eliminated from the fused cell to avoid the transfer of mutations to

the resulting embryo.

!ell em rane Repairo onditions of mechanical stress and pathogenic actions can lead to disruption

of certain patches or formation of pores in the cell membrane.

o (he secretory lysosomes fuse with the cell membrane at a location close to

the damaged patch.


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o (his results in the release of hydrolases outside the cell one of them, a

specialized hydrolase called acid sphingomyelinase -)&M/ causes the

internalization of damaged patch by the cell the fusion of the lysosome

with the membrane provides e!tra lipids and prevents constriction of the

cellular boundary.

/. What are the major steps that occur during phagoc!tosis. See+igure . - In phagocytosis, or 6cell eating,6 the cell engulfs debris, bacteria, or other sizable ob*ects

4hagocytosis occurs in specialized cells called phagocytes, which include macrophages,

neutrophils, and other white blood cells

&rocess

o Invagination produces a vesicle called a phagosome, which usually fuses with

one or more lysosomes containing hydrolytic enzyme

o Materials in the phagosome are bro'en down by these enzymes and degraded.


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-. 0ist some of the major functions of the c!tos eleton.

ytos'eleton networ' of fibers throughout the cell7s cytoplasm

that helps the cell maintain its shape and gives

support to the cell

$u'aryotic cells contain three main 'inds of

cytos'eletal filaments

o Microfilaments

o intermediate filaments

o microtubules

Functions

o plays important roles in cell movement

-using flagella, cilia, or lamellipodia/

o intracellular transport -the movement of

vesicles and organelles, for e!ample/

o cellular division..

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Study Exercise Biology 20 - 24