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Bio 1 (101-NYA-05) > Lecture 7 - The Cell II > Flashcards

Lecture 7 - The Cell II Flashcards

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1
Q

Define a nucleoid

A

Discrete concentration of DNA located within the cell’s interior

Place, not a thing

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2
Q

define plasmids

A

small circular molecules of DNA that carry a small number of genes

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3
Q

describe pili

A

threadlike hollow structures that extend from one bacterial cell to another that allow the transfer of plasmids

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4
Q

describe cytosol

A

liquid found inside the cells

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5
Q

describe cytoplasm

A

area within the plasma membrane, which comprises of the cytosol, the mitochondria, plastids, and other organelles (but not their internal fluids and structures) but not the nucleus.

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6
Q

Are organelles within the endomembrane system distinct?

A

no, they are interconnected

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7
Q

how do organelles within the endomembrane system communicate?

A

by budding vesicles (small membrane enclosed sacs)

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8
Q

what does the endomembrane system include?

A

nuclear envelope, endoplasmic reticulum, Golgi apparatus and visicles

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9
Q

describe the nucleus

A

stores DNA

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10
Q

Describe the nuclear envelope

A
  • defines the boundary of the nucleus

- consists of two membranes (inner and outer) is a lipid bilayer with associated proteins

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11
Q

describe nuclear pores

A

act as gateways allowing molecules to enter and leave the nucleus

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12
Q

describe the nucleolus

A

appears as a mass of densely stained granules and fibers

  • site where rRNA is synthesized
  • assembly site of large and small ribosomal subunits
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13
Q

are ribosomes part of the endomembrane system?

A

no

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14
Q

describe ribosomes

A
  • complexes made of rRNA and proteins (forming large and small subunits)
  • sites of protein synthesis, in which amino acids are assembled into polypetides
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15
Q

free ribosomes

A

found floating in the cytosol

* synthesize proteins that do not leave the inside of the cell*

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16
Q

bound ribosomes

A

attached to the endoplasmic reticulum membrane

synthesize proteins that are secreted or components of the plasma membrane

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17
Q

endoplasmic reticulum

A
  • continuous with the nuclear envelope
  • accounts for more than half of the total membrane in many eukaryotic cells
  • two distinct regions of the ER that differ in structure and function
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18
Q

rough endoplasmic reticulum

A
  • studded with ribosomes on the surface of the membrane
  • site of synthesis of proteins that are to be secreted
  • synthesis of membranes
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19
Q

smooth endoplasmic reticulum

A
  • outer surface lacks ribosomes
  • functions in diverse metabolic processes, which vary with cell type
  • synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poisons, storage of calcium ions
20
Q

testosterone, a steroid hormone is synthesized in the cells of the testes. These cells would therefore have extensive amounts of WHICH organelle?

A

SMOOTH E.R.

steroids = lipids
lipids are synthesized in the smooth E.R.

21
Q

golgi apparatus

A
  • looks like a series of flattened membrane sacs, called cisternae
  • stacked cisternae are surrounded by many small vesicles
  • not physically continuous with the E.R.
  • next stop for most vesicles budding from the ER
22
Q

primary roles of golgi apparatus

A
  • further modifies the lipids and proteins produced by the ER
  • acts as sorting station
  • synthesis of carbohydrates
23
Q

lysosomes

A
  • specialized vesicles derived from the Golgi
  • responsible for the intracellular digestion: degrade damaged or unneeded biomolecules, bacteria or other smaller organisms that have been engulfed
  • uses digestive enzymes and an internal environment with an acidic pH
24
Q

vacuoles

A
  • large vesicles derived from the endoplasmic reticulum and Golgi apparatus
  • perform a variety of functions:
  • food vacuole - formed by phagocytosis
  • contractile vacuole - in aquatic protists, pumps excess water
  • central vacuole - in plants, holds materials
25
Q

is the mitochondria part of the endomembrane system?

A

no

26
Q

what happens in the mitochondria

A

cellular respiration: a metabolic process that uses oxygen to generate ATP by extracting energy from sugars, fats and other fuels
** cellular respiration happens in the inner membrane

27
Q

how many mitochondria are in a cell?

A

some cells have a single large mitochondrion, more often a cell has hundreds to thousands of mitochondria (dependent on cell’s function)

tissues and organisms that require more energy have more mitochondria

28
Q

describe the mitochondria (its build)

A

enclosed by two membranes; outer membrane is smooth, inner membrane has infoldings called cristae

  • inner membrane divides mitochondrion into
  • inner membrane space: narrow region between the inner and outer membrane
  • mitochondrial matrix: contains enzymes, mitochondrial DNA and ribosomes.
29
Q

do animals have chloroplasts?

A

no

30
Q

chloroplasts

A

capture the energy of sunlight to synthesize sugars; a process known as photosynthesis

  • surrounded by double membrane and have an internal membrane-bound compartments called thylakoid
31
Q

thylakoid membrane

A

contains a specialized light-collecting molecules (eg. chloraphyll is the most common)

32
Q

what categories of cytoskeleton are found in eukaryotes vs animal cells

A

found in all eukaryotes:

  • microtubules
  • microfilaments

found only in animal cells
- intermediate filaments

33
Q

shape of microtubules

A

hollow rods constructed from protein dimer called tubulin

34
Q

microtubules function

A
  • shape and support the cell (compression resistant)
  • serve as tracks along which organelles can move
  • form cilia and flagella
  • involved in separating the chromosomes during cell division
35
Q

name examples of microtubules

A
  • flagella

- cilia

36
Q

flagella

A
  • long, few

- has undulating motion that generates force in the same direction as the flagellum’s axis

37
Q

cilia

A
  • short, many

- work like oars, with alternating power and recovery strokes

38
Q

centrosome

A
  • region located near the nucleus of animal cells considered to be a “microtubule organizing center”
  • are composed of 2 centrioles
  • are responsible for moving organelles and pulling the cell apart during cell division in animal cells
39
Q

do plants have a centrosome?

A

no

40
Q

microfilament structure

A
  • solid rods
  • also called actin filaments as they are built from molecules of actin
  • can form structural networks
41
Q

microfilament function

A

TENSION BEARING

  • 3D networks support cell shape (make up the core of microvilli)
  • important component of muscle cells
  • serve as tracks along which organelles with motor proteins can move
42
Q

intermediate filaments structure

A
  • found only in animal cells
  • not as frequently disassembled or reassembled as microtubules or intermediate filaments
  • especially sturdy (remain intact after cell death)
43
Q

intermediate filaments function

A
  • tension bearing

- reinforce the cell’s shape and fix the position of certain organelles

44
Q

path of a membrane protein

A
  • mRNA translated into polypeptide at a bound ribosome (on RER)
  • Polypeptide moves through RER and eventually buds off as a vesicle
  • vesicle moves along microtubules until it reaches Golgi apparatus where polypeptide is further altered
  • final polypeptide moves through Golgi cisternae and eventually buds off as a vesicle
  • vesicle moves along microtubules until it reaches membrane, where it will stay and perform its function
45
Q

what is common in animal cells but not plant cells?

A

intermediate filaments, centrosome, centrioles

46
Q

what is common in all plant cells but not all animal cells

A

chloroplasts
cell wall
central value

Bio 1 (101-NYA-05) (8 decks)

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