Unit 1: Properties of Cells Flashcards
1
Q
What are 2 statements that describe the definition of a cell?
A
- A unit capable of carrying out essential life processes
- A unit that can usually reproduce
2
Q
Which of the following structures do all cells share?
A
- cytoplasm
- ribosomes
- a membrane
- genetic material
3
Q
What are two reasons that eukaryotic cells may have a nucleus.
A
- to keep processes like transcription separate from other processes like translation which allows for more complex ways to regulate gene expression than are possible in prokaryotes
- to keep all of the molecules necessary within the nucleus at a high concentration
4
Q
What is cytoplasm in eukaryotic cells?
A
- the entire contents of the cell
5
Q
What is cytosol in eukaryotic cells?
A
- the region inside the cell, but outside the organelles
6
Q
Generally, what are the characteristics that define cells at the smallest unit of life. (3)
A
- all cells contain a stable blueprint of information in molecular form
- cells have a discrete boundary that separates the interior of the cell from its external environment
- cells have the ability to harness materials and energy from the environment
7
Q
What are the 3 principles of the cell theory? Explain what this means.
A
- all organisms are composed of one or more cells
- the cell is the fundamental unit of life
- cells arise from pre-existing cells
- there is no life without cells and the cell is the smallest unit of life
8
Q
Generally, which cells are bigger between bacterial cells and eukaryotic cells?
A
- eukaryotic cells are generally much bigger than bacterial cells
9
Q
Elaborate on how all cells contain a stable blueprint of information in molecular form (4)
A
- nucleic acids store and transmit information needed for growth, function, and reproduction
- the central dogma of molecular biology
- organisms require an accessible and reliable archive of information that help determine their structure and metabolic activity
- organisms must have the ability to reproduce do cells must be able to copy their archive of information rapidly and accurately
10
Q
replication
A
- the process of copying DNA so genetic information can be passed from cell to cell or from an organism to its progeny
11
Q
transcription
A
- the synthesis of RNA from a DNA template
12
Q
translation
A
- synthesis of polypeptide chain corresponding to the coding sequence present in a molecule of messenger RNA
13
Q
central dogma (2)
A
- originally, the idea that information flows from nucleic acids to proteins, but not in the opposite direction
- more generally, the view that information transfer in a cell usually goes from DNA to RNA to protein
14
Q
Elaborate on how cells have a discrete boundary that separates the interior of the cell from its external environment
A
- membranes define cells and spaces within cells
- membrane surrounds every cell and controls exchange of materials with the environment
15
Q
plasma/cell membrane
A
- a membrane that surrounds the cytoplasm of the cell, separating the inside of the cell from the outside of the cell
16
Q
cell wall (2)
A
- a structural layer external to the plasma membrane that helps maintain the shape and internal composition of the cell
- present in plants, fungi, many protists, archaeans, and bacteria
17
Q
organelles
A
- any one of several compartments in eukaryotes that divide the cell contents into smaller spaces specialized for different functions
18
Q
chloroplasts
A
- organelle in photosynthetic eukaryotes that converts energy of sunlight into chemical energy by synthesizing simple sugars
19
Q
mitochondria
A
- specialized organelles that are the site of respiration in eukaryotic cells, oxidizing chemical compounds such as sugars to carbon dioxide and transferring their chemical energy to ATP
20
Q
prokaryotes
A
- cells without a nucleus, including bacteria and archaeans
21
Q
eukaryotes
A
- cells with a nucleus, including animals, plants, fungi, and protists
22
Q
Elaborate on how cells have the ability to harness materials and energy from the environment
A
- metabolism converts energy from the environment into a form that can be used by cells
- cells can harness energy from the environment and convert it into a form that fells can use
23
Q
List the 3 domains that comprise the tree of life.
A
- bacteria
- archaea
- eukaryotes
24
Q
What does the tree of life tell us? (3)
A
- most of life’s diversity, and so most of its deep evolutionary history, is microbial
- eukaryotes are hypothesized to have descended from within the Archaea
- all plants and animals lie on branches within Eukarya
25
Q
Bacteria (4)
A
- one of the 3 domains
- consisting of single-celled organisms with a single circular chromosome but no nucleus that divide by binary fission
- they differ from archaeans in many aspects of their cell and molecular biology
- no membrane-bounded nuclei, no energy-producing organelles, no sex
26
Q
Archaea (3)
A
- one of the 3 domains
- consisting of single celled organisms with a single circular chromosome and no nucleus that divide by binary fission
- differ from bacteria in many aspects of their cell and molecular biology
27
Q
Eukarya (the eukaryotes)
A
- one of the 3 domains of life
- cells have a true nucleus and divide by mitosis
28
Q
Discuss unicellular versus multicellular organisms (2)
A
- every known cell is either s single cell or an ensemble of a few to many cells
- most bacteria, yeasts, and tiny algae can spend their lives as single cells, in contrast plants and animals contain billions to trillions of cells that function in a coordinated fashion
29
Q
Discuss varying cell shape and size (3)
A
- skin cell size is about 0.1mm in diameter and many bacteria are less than a micrometer long
- some nerve cells extend slender projections known as axons for distances as great as a meter
- cannon-ball sized egg ostrich is a cell
30
Q
metabolism (3)
A
- chemical reactions where cells convert energy from one form to another and build and break down molecules
- reactions are required to sustain life
- regardless of source of energy, all organisms use metabolism and in the process, release energy in a stored chemical form called adenosine triphosphate
31
Q
ATP (adenosine triphosphate)
A
- molecule enables cells to carry out all sorts of work including growth, division, and transporting substances into and out of the cell
32
Q
Describe some properties of prokaryotes.
A
- prokaryotes do not have . nucleus: there is no physical barrier separating the genetic material from the rest of the cell, transcribed mRNA is immediately translated into proteins by ribosomes
- DNA is concentrated in a discrete region of the cell interior known as the nucleoid
- organisms absorb nutrients from the environment
- very small cell size, typically 1-2 micrometers in diameter or smaller: large amount of membrane surface area is available for absorption relative to the volume of the cell that it serves
- lack extensive internal organization characteristics of eukaryotes
33
Q
plasmids (3)
A
- additional small circular molecules of DNA that are not essential for the cell’s survival
- commonly transferred between bacteria through action of threadlike structures known as pili, which extend from one cell to another
- genes for antibiotic resistance are often transferred this way as they may contain genes that have adaptive value under specific environmental conditions
34
Q
Describe some properties of Eukaryotes (3)
A
- defined by presence of nucleus: houses vast majority of cell’s DNA and nuclear membrane allows for more complex regulation of gene expression than is possible in prokaryotic cells
- DNA is transcribed to RNA in the nucleus, then RNA molecules carry the genetic message from inside the nucleus to outside the nucleus , where they instruct the synthesis of proteins
- have remarkable internal array of membranes that define compartments, called organelles, that divide the cell contents into smaller spaces specialized for different functions
35
Q
cytoplasm
A
- the entire contents of the cell other than the nucleus
36
Q
How does bacteria and eukaryotic DNA differ?
A
- bacteria cell DNA is present in a single circular chromosome
- eukaryotic cell DNA exist as multiple linear chromosomes
37
Q
How do cell processes change in bacteria cells that lack membrane-bounded organelles
A
- cell processes, such as metabolism, are carried out by proteins that float freely in the cytoplasm or are embedded in the plasma membrane
38
Q
What is the structural support for bacteria? (3)
A
- a cell wall made of peptidoglycan, a complex polymer of sugars and amino acids: some have thick walls made up of multiple layers while others have thin walls surrounded by an outer layer of lipids
- careful studies show that bacteria do possess internal scaffolding of proteins that play important role in determining the shape, polarity, and other spatial properties of bacterial cells
39
Q
Why are bacteria cells so small? (3)
A
- a small cells has more surface area in proportion to its volume, and the interior parts of a small cell are closer to the surrounding environment than those of a larger cell
- slowly diffusing molecules do not have to travel far to reach every part of a small cell’s interior
- as cell size increases it becomes harder to supply the cell with all the materials needed for growth
40
Q
What is endosymbiosis?
A
- certain organelles within eukaryotic cells resemble prokaryotic cells (endosymbionts)
41
Q
Why are two organelles that are notable for endosymbiosis and why?
A
- chloroplasts and mitochondria are notable in this regard because:
1. they are surrounded by two membranes
2. their inner membranes have structures that closely resemble certain prokaryotic cells
3. they contain circular genomes that code for genes that are very similar to bacterial genes
