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+ BIOL 112 > 1.3 The Cell > Flashcards

1.3 The Cell Flashcards

1
Q

What is a cell?

A

simplest self-reproducing entity that can exist as an independent unit of life

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2
Q

Describe different cell sizes.

A
  • cells that make up layers of skin are ~100 mcirometers, or 0.1 mm, in diameter
  • many bacteria are less than a micrometer long
  • some nerve cells in humans extend slender projections known as axons for distances as great as a meter
  • cannonball-size egg of an ostrich is a single giant cell
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3
Q

What is the stable blueprint of information in molecular form that all cells contain?

A
  • have a discrete boundary that separates the interior of the cell from its external environment
  • they have the ability to harness materials and energy from the environment
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4
Q

What do nucleic acids do?

A

store and transmit information needed for growth, function, and reproduction

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5
Q

What is the first essential feature of a cell?

A

its ability to store and transmit information

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6
Q

How do cells accomplish its ability to store and transmit information?

A

cells require a stable archive of information that encodes and helps determine their physical attributes

organisms require an accessible and reliable archive of information that helps determine their structure and metabolic activities

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7
Q

How do cells reproduce?

A

cells must be able to copy their archive of information rapidly and accurately

in all organisms, the information archive is remarkable molecule known as DNA

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8
Q

What is DNA?

A

a double-stranded helix, with each strand made up of varying sequences of four different kinds of molecules connected end to end

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9
Q

What makes DNA special?

A

the arrangement of the four different kinds of molecular subunits, they provide a four-letter alphabet that encodes cellular information

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10
Q

What does the information encoded in DNA direct?

A

the formation of proteins, the key structural and functional molecules that do the work of the cell

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11
Q

What part of a cell depends on proteins?

A

internal architecture
shape
ability to move
various chemical reactions

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12
Q

How does the information stored in DNA direct the synthesis of proteins?

A

first, existing proteins create a copy of the DNA’s information in the form of a closely related molecule called RNA

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13
Q

What is RNA?

A

ribonucleic acid

- a molecule chemically related to DNA that is synthesized by proteins from a DNA template

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14
Q

What is transcription?

A

the synthesis of RNA from a DNA template, the copying of information from one form into another

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15
Q

What is translation?

A

after transcription, specialized molecular structures within the cell then “read” the RNA molecule to determine which building blocks to use to create a protein

translation converts information stored in the language of nucleic acids to information in the language of proteins

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16
Q

What is the central dogma of molecular biology?

A

the idea that information flows from nucleic acids to proteins, but not in the opposite direction

the view that information transfer in a cell usually goes from DNA to RNA (specifically mRNA) to protein

*figure 1.13 textbook

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17
Q

What does the central dogma describe?

A

the basic flow of information in a cell and, while there are exceptions, it constitutes a fundamental principle in biology

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18
Q

How are specific segments of DNA defined?

A

as proteins are ultimately encoded by DNA, we can define specific segments of DNA according to the proteins that they encode

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19
Q

What is a gene?

A

stretch of DNA that affects one or more traits in an organism, usually through an encoded protein or noncoding RNA

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20
Q

What is replication?

A

process of copying DNA so genetic information can be passed from cell to cell or from an organism to its progeny

21
Q

What does DNA’s double-stranded helical structure allow?

A

each organism’s DNA can be stably and reliably passed from generation to generation

22
Q

What happens to the double helix during replication?

A

each strand of the helix serves as a template for a new strand

23
Q

Why is replication necessarily precise and accurate?

A

because mistakes introduced into the cell’s information archive may be lethal to the cell

errors in DNA can and do occur during the process of replication, and environmental insults can damage DNA as well

24
Q

What are mutations?

A

any heritable change in genetic material, usually a change in the nucleotide sequence of a gene

they can spell death for a cell, or they can lead to the variations that underlie the diversity of life and the process of evolution

25
Q

What is the second essential feature of all cells?

A

a plasma membrane that separates the living material within the cell from the nonliving environment around it

*figure 1.14 textbook

26
Q

Describe the plasma membrane.

A
  • there is an active and dynamic interplay between cells and their surroundings that is mediated by the plasma membrane
  • all cells require sustained contributions from their surroundings, both simple ions and the building blocks required to manufacture macromolecules, they also release waste products into the environment
  • controls the movement of materials into and out of the cell
27
Q

What do cells have internally?

A

internal membranes that divide the cell into discrete compartments, each specialized for a particular function

28
Q

What is the nucleus?

A

compartment of the cell that houses the DNA in chromosomes

29
Q

What does the nuclear membrane do?

A

like the plasma membrane, it selectively controls movement of molecules into and out of it

30
Q

What is cytoplasm?

A

contents of the cell other than the nucleus, space outside the nucleus

31
Q

What are prokaryotes?

A

cells without a nucleus

most are single-celled organisms, some have simple multicellular forms

32
Q

What are eukaryotes?

A

cells with a nucleus

exist as single cells or multicellular organisms

33
Q

What do prokaryotes do?

A
  • some live in peaceful coexistence with humans, inhabiting out gut and aiding digestion
  • others cause disease - salmonellosis, tuberculosis, and cholera are familiar examples of such bacterial diseases
34
Q

What does the success of prokaryotes depend on?

A

depend in part on their small size, their ability to reproduce rapidly, and their ability to obtain energy and nutrients from diverse sources

35
Q

What do muscle cells do?

A

contract

36
Q

What do red blood cells do?

A

carry oxygen to tissues

37
Q

What do skin cells do?

A

provide an external barrier

38
Q

What are the 3 domains of life?

A

Bacteria, Archaea, and Eukarya

39
Q

What are Bacteria and Archaea?

A

mostly single-celled microorganisms that lack a nucleus and are therefore prokaryotes

many Archaea flourish under seemingly hostile conditions, such as those found in the hot springs of Yellowstone national Park

40
Q

What are Eukarya?

A

have a nucleus and are eukaryotic

41
Q

What is a third key feature of cells?

A

the ability to harness energy from the environment

42
Q

Where do organisms acquire energy from?

A

two sources:

  • sun
  • chemical compounds
43
Q

What is metabolism?

A

chemical reactions occurring within cells that convert molecules into other molecules and transfer energy in living organisms

the term describes chemical reactions by which cells convert energy from one form to another and build and break down molecules

these reactions are required to sustain life

44
Q

Where does ATP come from from organisms?

A

regardless of their source of energy, all organisms use chemical reactions to break down molecules and in the process, release energy stored in a chemical form called adenosine triphosphate

45
Q

What does ATP do?

A

enables cells to carry out all sorts of work, including growth, division, and moving substances into and out of the cell

46
Q

What is a virus?

A
  • genetic material that requires a cell to carry out its functions
  • an agent that infects cells
  • usually smaller and simpler than cells
47
Q

Why aren’t viruses the smallest unit of life?

A

consider the three essential features of cells (capacity to store and transmit info, selectively permeable membrane, ability to harness energy from the environment)

have a stable archive of genetic information, DNA or RNA, surrounded by a protein coat and sometimes a lipid envelope BUT viruses cannot harness energy from the environment

therefore, on their own, viruses cannot read and use the information contained in their genetic material, nor can they regulate the passage of substances across their protein coats or lipid envelopes the way cells do

to replicate, they require a cell

48
Q

How does a virus infect a cell?

A

by binding to the cell’s surface, inserting its genetic material into the cell, and, in most cases, using the cellular machinery to produce more viruses

they can then lyse, or break, the cell, enabling the new viruses to seek out and infect more cells

in some cases, genetic material of the virus becomes integrated into the DNA of the host cell

+ BIOL 112 (30 decks)

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