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Bio - Cell Structure Test > Cell Structure > Flashcards

Cell Structure Flashcards

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Biology 101 flashcards
1
Q

What is the cell theory

A

All living organisms are composed of one or more cells
Cells are the smallest units of life
All cells come from pre-existing cells

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2
Q

What structures are common to all cells

A

Plasma membrane, cytoplasm, DNA, ribosomes

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3
Q

What is the plasma membrane?

A

The membrane is a bilayer formed from phospholipids as a consequence of their hydrophobic and hydrophilic regions.

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4
Q

What is the cytoplasm?

A

The fluid that fills cells and serves several important functions. Cytosol is the liquid part of the cytoplasm. It has solutes such as salts, fatty acids, sugars, amino acids and proteins.

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5
Q

What is DNA?

A

The polymer carries genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses.

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6
Q

What are ribosomes?

A

Ribosomes are molecular machines found in all living cells, responsible for synthesizing proteins. They read the genetic code carried by messenger RNA (mRNA), which is transcribed from DNA, and translate it into a specific sequence of amino acids to form proteins. Ribosomes are composed of two subunits each made up of ribosomal RNA (rRNA) and proteins.

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7
Q

Characteristics of a prokaryotic cell

A

Cytoplasm
Ribosomes
Cell membrane: regulates what moves in and out of the cell
Cell wall: provides shape and lets the cell withstand turgor pressure
Pili: allows cell to attach to surfaces and swap DNA with other cells
Capsule: keeps cell from dehydrating and adhere to surfaces
Flagellum: long extensions used in cell locomotion

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8
Q

Where can prokaryotic cell DNA be found

A
  1. Nucleoid: main DNA of the cell.
    DNA is not enclosed in a membrane, it is found freely in the cytoplasm DNA is a single loop
    DNA is not wrapped around proteins (termed “naked”)
  2. Plasmid: extra piece(s) of DNA
    Circular and naked
    Smaller than main nucleoid DNA
    Replicates independently of the nucleoid DNA
    Not found in all prokaryotic cells
    Can be shared between bacteria
    Often contain genes for antibiotic resistance
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9
Q

What is the nucleus?

A
  • Contains the DNA which stores information for making proteins via transcription and translation.
  • Contains the nucleolus, which is where ribosome subunits are made.
  • Has double membrane with pores through it which allows cells to separate the activities of gene transcription and translation.
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10
Q

What is the rough endoplasmic reticulum?

A

The RER is a series of connected flattend membranous sacs that play a central role in the synthesis and transport of amino acids.
It has ribosomes which synthesize the amino acid and release it to the inside of the RER.

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11
Q

What is the smooth endoplasmic reticulum?

A
  • in contrast to the RER, smooth endoplasmic reticulum lacks ribosomes and is not involved in protein synthesis.
  • The main functions of SER are the synthesis of phospholipids and cholesterol for the formation and repair of membranes.
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12
Q

What is the golgi apparatus?

A

The Golgi sorts, concentrates and packs proteins into vesicles.
Depending on the contents, the vesicles are dispatched to one of three destinations:
- Within the cell, to organelles called lysosomes.
- The plasma membrane of the cell.
- Secretion to the outside of the cell via exocytosis.

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13
Q

What are vesicles?

A

Vesicles are membrane bound sacs that contain and transport materials within cells.
* Transport vesicles move molecules between locations inside the cell by budding off one organelle compartment and fusing with another.
* Secretory vesicles secrete molecules from the cell via exocytosis. They are also how new phospholipids are added to the cell membrane.

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14
Q

What are lysosomes?

A
  • Lysosomes are small spherical organelles, enclosed by a single membrane.
  • Contain enzymes that work in oxygen-poor areas and lower pH
  • The enzymes digest large molecules to degrade and recycle the components of the cell’s own organelles when they are old or damaged, or if the cell is ‘starving’ in the absence of nutrients.
  • Also has an immune defense function, by digesting pathogens that have been engulfed by phagocytes.
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15
Q

What is the mitochondria?

A
  • Mitochondria are adapted for production of ATP by aerobic cellular respiration. The mitochondrion is surrounded by a double membrane.
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16
Q

What are chloroplasts?

A

Chloroplasts are adapted for photosynthesis, which captures light energy and uses it with water and carbon dioxide to produce glucose.
* Within the chloroplasts are light-absorbing pigments such as chlorophyll, which give the chloroplast its characteristic green colour.
* Chloroplasts evolved by endosymbiosis.

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17
Q

What are vacuoles?

A

Mature plant cells have a central vacuole that occupies 30% - 90% of the volume of the cell.
In addition to water storage, the main role of the vacuole is to maintain turgor pressure against the cell wall. The turgor pressure is mechanism the plants use to remain upright.

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18
Q

What is the cytodskeleton?

A

Present in both prokaryotic and eukaryotic cells, the cytoskeleton is not considered to be an organelle.
The cytoskeleton helps cells maintain their shape, organizes cell parts and enables cells to move and divide. Several different components work together to form the cytoskeleton, including:
Microtubules
Actin filaments
Intermediate filaments

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19
Q

What are microtubules?

A

Microtubules are polymers of a protein called tubulin E and form part of the cytoskeleton.
Microtubules are used for the intracellular transport of organelles and the separation of chromosomes during mitosis.

20
Q

What are centrioles?

A

Centrioles are paired cylindrical-shaped organelles composed of nine groups of three microtubules.
Functions of centrioles include:
* Arrangement of the mitotic spindle during cell division.
* Serve as anchor points for microtubules in the cytoplasm and for cilia and flagella (when modified to become a basal body).
* A few eukaryotic cell types have lost their centrioles including most fungi and vascular plants (but not the more primitive mosses and ferns).

21
Q

What are cilia and flagella?

A

Cilia and flagella are extensions from the cell surface which aid in cell movement. They are formed from modified centrioles called a basal body.
* If the protrusions are short and numerous they are termed cilia. Cilia beat in coordination with each other.
* If the protrusions are longer and less numerous (usually only one or two they are termed flagella. Flagella move independently of each other.

22
Q

What is homeostasis?

A
  • Living organisms keep their internal environments within a certain range (they maintain a stable internal condition), despite changes in their external environment.
  • Even single celled organisms maintain homeostasis, for example by keeping concentrations of water and minerals within certain levels.
  • keeping balance
23
Q

What is metabolism?

A
  • Metabolism is the sum of all the chemical reactions in a cell.
  • Viruses lack metabolism, a reason they are not considered to self-sustaining life
24
Q

What is nutrition?

A

All life obtains energy and matter.
Autotrophs use external energy sources (usually the sun) to synthesize carbon compounds from simple inorganic substances
* Heterotrophs use carbon compounds obtained from other organisms to synthesize the carbon compounds that they require

25
Q

Definition of movement

A

Adaptations for movement are a universal feature of living organisms. Sessile organisms stay in one place, whereas motile organisms are mobile.

26
Q

What is excretion?

A

Excretion is a process in which metabolic waste is eliminated from an organism.
In humans, excretion primarily occurs via lungs and kidneys.
In many plants, excretion occurs via leaves, roots and stem
In unicellular organisms, excretion occurs through the cell membrane, which is one reason cells must have a large surface area to volume ratio

27
Q

What is growth?

A

All living things can grow and/or develop the lifespan.
Growth is the increase in size and mass of an organism.
Development is the transformation of the organism through its lifespan.

28
Q

What is response to stimuli?

A

All life can recognize and respond to changes in environmental conditions. Even single celled organisms can recognize what is going on around them, and respond to changes in the environment.
How do cells recognize their environment? Often the first step is stimulation of a protein embedded in the cell membrane.
Chemoreceptors: stimulated by changes in the chemical concentration of substances
Baroreceptors: stimulated by changes in pressure
Thermoreceptors, stimulated by changes in temperature
Photoreceptors. stimulated by light energy

29
Q

What are the types of reproduction?

A

Sexual reproduction involves two parents and the fusion of haploid sex cells from each paren.
Meiosis allows for a sexual life cycle with fusion of gametes.
Sexual reproduction produces offspring that are genetically unique and increases genetic variation within a species.
Asexual reproduction involves only one parent.
Asexual reproduction produces offspring that are all genetically identical to the parent.
* Binary fission and mitosis are mechanism of asexual reproduction.

30
Q

What are the functions of life?

A

Homeostasis
Metabolism
Nutrition
Movement
Excretion
Response to stimuli
Reproduction

31
Q

Properties of animal cells

A

Animals are all multicellular eukaryotes without a cell wall
Animals are holozoic (eat other organisms with internal digestion of nutrients).
The animal kingdom is the largest kingdom with 1 million known species. Although, the number of known species if likely an artifact of human bias towards studying animals!

32
Q

Properties of fungus cells

A

Fungi are eukaryotes with a cell wall made of a molecule called chitin.
Can be unicellular (i.e. yeast) or multicellular (mushrooms).
Most fungi are saprotrophs - this means they secrete digestive enzymes into their environment and then absorb the nutrients into their body after there has been external digestion!
Some fungi are parasitic.
Fungi are the principal decomposers

33
Q

Properties of plant cells

A

Plants are all multicellular eukaryotes with a cellulose cell wall
With just a few exceptions, plants are autotrophs (organisms that make their own food. Without plants, life on Earth would not exist as we know it! Plants feed almost all the heterotrophs (organisms that eat other organisms) on Earth.
There are an estimated 300,000 species of plants known to science.

34
Q

What are plastids?

A

Plastids are double-membrane organelles which are responsible for manufacturing and storing of food.

35
Q

What do all eukaryotic cells have in common?

A

Nucleus
Free and bound 80s ribosomes
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Golgi apparatus
Vesicles
Lysosome
Mitochondria
Cytoskeleton

36
Q

Where are plastids present?

A

Only in plant cells - Present, including chloroplasts for photosynthesis and amyloplasts to store starch.

37
Q

What cells are cell walls present in?

A

Fungus - composed of chitin
Plant - composed of mostly cellulose

38
Q

What cells are vacuoles present in?

A

Animal cell - Present as small, temporary structures that expel excess water or other waste products.
Fungus/Plant cell - Present as a large, permanent organelle. Used to store water and to cause turgor pressure against the cell wall.

39
Q

What are centrioles?

A

Centrioles are paired cylindrical-shaped organelles composed of nine groups of three microtubules organized with radial symmetry.

40
Q

What cells are centrioles present in?

A

Animal - Present. Used to arrange the mitotic spindle during cell division and to serve as anchor points for cilia and flagella.
Fungus - Are absent from most fungi, except a small number that have a swimming male gamete.
Plant - Are present in the male gametes of moss and ferns. Are absent in all conifers and flowering plants.

41
Q

What cells are cilia and flagella present in?

A

Animal - Present in many animal cells, including in the male gamete
Fungus - Are absent from most fungi, except a small number that have a swimming male gamete.

42
Q

Discrepancy of red blood cells

A

Red blood cells are the most common blood cells and function in oxygen transport in vertebrates.
During their maturation, red blood cells discard their nucleus and mitochondria. This makes the cells very small, increasing their surface area to volume ratio for efficient gas exchange and the ability to move through narrow capillary vessels.

Discrepancy: a eukaryotic cell without a nucleus or mitochondria!

43
Q

Discrepancy of Aseptate Fungal Hyphae

A

Hyphae are the tubular projections of multicellular fungi that form an underground filamentous network (mycelium). Fungal hyphae are sometimes not divided up into individual cells (called aseptate hyphae), resulting in a continuous cytoplasm along the length of the hyphae.

Discrepancy: Aseptate hyphae are not made of clearly defined individual cells, rather continuous structures with multiple nuclei.

44
Q

Discrepancy of Skeletal Muscle

A

Skeletal muscle fiber cells result from the fusion of multiple unicellular cells. This results in a single large cell that has multiple nuclei.

Discrepancy: a very large eukaryotic cell with more than one nucleus!

45
Q

Discrepancy of Phloem Sieve Tube Element

A

Sieve tube elements are specialized cells that are part of the phloem, the tissue that transports organic compounds made during photosynthesis throughout a plant. more space for transport of phloem sap.
Sieve tube elements lose their nucleus and other organelles during their development. This allows the cells to have

Discrepancy: a eukaryotic cell without organelles!

46
Q

What are chloroplasts?

A

Chloroplasts are adapted for photosynthesis Which captures light energy and uses it with water and carbon dioxide to produce glucose
Bound by a double membrane
Found only in plant cells
Have internal stacks of thylakoid membrane

47
Q

What are microvilli?

A

Microvilli are protrusions of the cell membrane that increase the surface area for absorption.
Many short extensions of the cell membrane
Usually shorter and more tightly packed than cilia
Do not have a 9+2 arrangement of microtubules

Bio - Cell Structure Test (3 decks)

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