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Biology 235 > Chapter 3: The Cellular Level - PART 2 > Flashcards

Chapter 3: The Cellular Level - PART 2 Flashcards

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1
Q

_______consists of all the cellular contents between the plasma membrane and the nucleus, and has two components:

A

cytoplasm 1) the cytosol and (2) organelles (tiny strucutres performing funcitons in the cell)

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2
Q

define cytosol (intracellular fluid)

A

fluid portion of the cytoplasm that surrounds organelles

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3
Q

What is the cytoskeleton?

A

a network of protein filaments that extends throughout the cytosol

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4
Q

what are the 3 types fila- mentous proteins that contribute to the cytoskeleton?

A

microfilaments, intermedi- ate filaments, and microtubules.

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5
Q

What are microfilaments? what are their 2 general funcitons?

A

thinnest elements of the cytoskeleton composed of the proteins actin and myosin and are most prevalent at the edge of a cell 1) help generate movement and 2) provide mechanical support

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6
Q

Microfilaments also provide mechanical support for cell extensions called _____

A

microvilli - microscopic fingerlike projections of the plasma membrane

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7
Q

what are intermediate filaments? what is their function?

A

thicker than microfilaments but thinner than mi- crotubules - help stabilize the position of organelles such as the nucleus and help at- tach cells to one another.

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8
Q

what are microtubules? function?

A

the largest of the cytoskeletal components and are long, unbranched hollow tubes composed mainly of the protein tubulin - help determine cell shape and function in movement of organelles

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9
Q

The assem- bly of microtubules begins in an organelle called the _____

A

centrosome

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10
Q

what two components does centrosome consist of?

A

1) two centrioles - cylindrical structures, each composed of 9 clusters of 3 microtubules 2) Surrounding the centrioles is pericentriolar material which contains hundreds of ring-shaped complexes composed of the protein tubulin

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11
Q

What are cilia

A

numerous, short, hairlike projec- tions that extend from the surface of the cell (each = 20 microtubules) - . The coordinated movement of many cilia on the surface of a cell causes the steady movement of fluid along the cell’s surface. - used in respiratory tract

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12
Q

What are flagella

A

similar in structure to cilia but are typically much longer and move an entire cell. ex. sperm cell’s tail

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13
Q

What are ribosomes?

A

sites of protein synthesis -contain ribosomal RNA (rRNA) and 50 proteins

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14
Q

what is the endoplasmic reticulum?

A

A network of membranes in the form of flattened sacs or tubules - extends from the nuclear envelope throughout the cytoplasm

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15
Q

What are the two types of ER?

A

1) Rough ER from nuclear membrane is folded into a series of flattened sacs. outer surface of is studded with ribosomes, the sites of protein synthesis (glycoproteins and phospholipids) 2) Smooth ER extends from the rough ER to form a network of membrane tubules - and synthesizes fatty acids and steroids

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16
Q

What is the Golgi complex

A

Modifies, sorts, packages, and transports proteins received from the rough ER. and forms secretory vesicles that discharge the processed proteins

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17
Q

What are lysosomes? 4 functions?

A

membrane-enclosed vesicles that from the Golgi complex

> contain digestive and hydrolytic enzymes that break down molecules (such as proteins)

> lysosomal membrane includes transporters that move the final products of digestion into the cytosol.

> implement autophagy (digestion of warn out organelles) and autolysis (digestion of entire cell)

> accomplish extracellular digestion

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18
Q

what are the functions of centrosomes?

A
  1. The pericentriolar material of the centrosome contains tubulins that build microtubules in nondividing cells. 2. The pericentriolar material of the centrosome forms the mitotic spindle during cell division.
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19
Q

What are peroxisomes?

A

similar in structure to lysosomes, but smaller - very abundant in the liver

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20
Q

What enzymes do peroxisomes contain? what are the functions of each? give ex.

A

contain oxidase (enzyme) that removes O2 from organic substances and catalase which decomposes H202 (the by product of oxidation) ex. amino acids and fatty acids are oxidized in peroxisomes as part of normal metabolism, and toxic substances like alcohal are also oxidized

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21
Q

What are Proteasomes? what is their function?

A

tiny barrel- shaped structures consisting of four stacked rings of proteins around a central core >Continuous destruction of un- needed, damaged, or faulty proteins is their function

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22
Q

What are mitochondria? what is their function (2) and structure?

A

> they generate most of the ATP through aerobic respiration active cells (muscle, liver) have more of them

> play important and early role in apoptosis the orderly, genetically programmed death of a cell

>mitochondrion consists of an outer mitochondrial membrane and an inner mitochondrial membrane with a small fluid-filled space between them. The inner mitochondrial membrane contains a series of folds called mitochondrial cristae. The central fluid‐filled cavity of a mitochondrion, enclosed by the inner mitochondrial membrane, is the mitochondrial matrix.

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23
Q

mitochondrial genes are inher- ited only from your _____

A

mother

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24
Q

What is the nucleus

A

a spherical or oval-shaped structure that usually is the most prominent feature of a cell

25
Q

A double membrane called the ________ separates the nucleus from the cytoplasm.

A

nuclear envelope (made of lipid bilayers)

26
Q

. The outer membrane of the nuclear envelope is continuous with _______ and resembles it in structure.

A

rough ER

27
Q

Many openings called ______ extend through the nuclear enve- lope.

A

nuclear pores

28
Q

What do nuclear pores do?

A

control the movement of substances between the nucleus and the cytoplasm. Small molecules and ions move through the pores passively by diffusion

29
Q

Inside the nucleus are one or more spherical bodies called _______that function in producing ________

A

nucleoli, ribosomes

30
Q

Each nucleolus is simply a cluster of what 3 things?

A

pro- tein, DNA, and RNA

31
Q

. Nucleoli are the sites of synthesis of what?

A

rRNA and assembly of rRNA and pro- teins into ribosomal subunits.

32
Q

Within the nucleus are most of the cell’s hereditary units, called ____-, which control what?

A

genes > control cellular structure and direct cellular activi- ties

33
Q

Genes are arranged along _________ . How many does each body cell have?

A

chromosomes 46 chro- mosomes, 23 inherited from each parent.

34
Q

What is a chromosome?

A

a long molecule of DNA that is coiled together with several proteins

35
Q

This complex of DNA, proteins, and some RNA is called _______

A

chromatin

36
Q

The total genetic infor- mation carried in a cell or an organism is its _____

A

genome

37
Q

In the process called ________, a gene’s DNA is used as a template for synthesis of a specific protein

A

gene expression

38
Q

What are teh 2 stages of protein synthesis?

A

1) transcription, the information encoded in a specific region of DNA is transcribed (copied) to produce a specific mole- cule of RNA (ribonucleic acid). 2) translation, the RNA attaches to a ribosome, where the informa- tion contained in RNA is translated into a corresponding sequence of amino acids to form a new protein molecule

39
Q

DNA and RNA store genetic information as sets of three nu- cleotides. A sequence of three such nucleotides in DNA is called a ______. Each DNA base triplet is transcribed as a comple- mentary sequence of three nucleotides, called a _____ which specifies a particular __________

A

base triplet, codon, amino acid

40
Q

What is the genetic code?

A

the set of rules that relate the base triplet sequence of DNA to the cor- responding codons of RNA and the amino acids they specify.

41
Q

what Three types of RNA are made from the DNA template:

A
  1. Messenger RNA (mRNA) directs the synthesis of a protein. 2. Ribosomal RNA (rRNA) joins with ribosomal proteins to make ribosomes. 3. Transfer RNA (tRNA) binds to an amino acid until it’s incorporated into a protein dur- ing translation. One end carries an amino acid, and the opposite end has an anticodon. the tRNA anticodon attaches to the mRNA codon.
42
Q

What does RNA polymerase do?

A

catalyzes transcription of DNA

43
Q

The segment of DNA where transcription begins, there is a special nucleotide sequence called a_________, it is located near the beginning of a gene.

A

Promotor - This is where RNA polymerase attaches to the DNA

44
Q

adenine in the DNA template pairs with ______, not thymine, in RNA

A

uracil (U)

45
Q

Transcription of the DNA strand ends at another special nu- cleotide sequence called a _______

A

terminator

46
Q

what are the 6 stages of translation

A
  1. mRNA binds to ribosomal subunit at binding site. initiator tRNA, binds to start codon (AUG) - translation begins. The tRNA anticodon (UAC) attaches to the mRNA codon (AUG) by pairing complementary bases. AUG is the codon for methionine = methionine is always the first amino acid in a growing polypeptide.
  2. the large ribosomal subunit attaches to the small ribosomal subunit–mRNA complex, creating a functional ribosome. The initiator tRNA, with its amino acid (methionine), fits into the P site of the ribosome.
  3. The anticodon of another tRNA with its attached amino acid, pairs with the second mRNA codon at the A site of the ribosome.
  4. A component of the large ribosomal subunit catalyzes the formation of a peptide bond between methionine, which separates from its tRNA at the P site, and the amino acid carried by the tRNA at the A site.
  5. After peptide bond formation, the tRNA at the P site detaches from the ribosome, and the ribosome shifts the mRNA strand by one codon. The tRNA in the A site bearing the two-peptide protein shifts into the P site, allowing another tRNA with its amino acid to bind to a newly exposed codon at the A site. Steps 3 through 5 occur repeatedly, and the protein lengthens progressively.
  6. Protein synthesis ends when the ribosome reaches a stop codon, which causes the completed protein to detach from the final tRNA. When the tRNA vacates the ribosome, the ribosome splits into its large and small subunits.
47
Q

What is somatic cell division?

A

: a cell undergoes a nuclear division called mitosis and a cytoplasmic division called cytokinesis to produce two genetically identical cells, each with the same number and kind of chromosomes as the original cell.

48
Q

What is reproductive cell division?

A

the mechanism that produces gametes, the cells needed to form the next generation of sexually reproducing organisms.

49
Q

What is meiosis?

A

a special two- step division in which the number of chromosomes in the nucleus is reduced by half.

50
Q

what are homologous chromosomes

A

The two chromosomes that make up each pair of chromosomes inherited by each parent. They contain similar genes arranged in the same (or almost the same) order.

51
Q

What are the sex chromosomes?

A

, X and Y: In females the homologous pair of sex chromosomes consists of two large X chromosomes; in males the pair consists of an X and a much smaller Y chromosome.

52
Q

What is interphase?

A

: the cell replicates its DNA It also produces additional organelles and cytosolic components in anticipation of cell division.

53
Q

What are the 4 stages of interphase?

A
  • G1 phase: is the interval between the mitotic phase and the S phase. During G1, the cell is metabolically active; it replicates most of its organelles and cytosolic components but not its DNA. Replication of centrosomes also begins in the G1 phase.
  • G0 state: Cells that remain in G1 for a very long time, perhaps destined never to divide again. Most nerve cells are in the G0 phase.
  • S phase: the interval between G1 and G2, lasts about 8 hours. During the S phase, DNA replication occurs. As a result of DNA replication, the two identical cells formed during cell division later in the cell cycle will have the same genetic material.
  • G2 phase: is the interval between the S phase and the mitotic phase. It lasts 4 to 6 hours. During G2, cell growth continues, enzymes and other proteins are synthesized in preparation for cell division, and replication of centrosomes is completed.
54
Q

Describe the four stages of mitosis?

A
  • prophase: the chromatin fibers condense and shorten. Each prophase chromosome consists of a pair of identical strands called chromatids. Later in prophase, tubulins in the pericentriolar material form the mitotic spindle. As the microtubules lengthen, they push the centrosomes to the poles (ends) of the cell so that the spindle extends from pole to pole.
  • metaphase: the microtubules of the mitotic spindle align the centromeres of the chromatid pairs at the exact center of the mitotic spindle. This midpoint region is called the metaphase plate.
  • anaphase: the centromeres split, separating the two members of each chromatid pair, which move toward opposite poles of the cell. Once separated, the chromatids are termed chromosomes. As the chromosomes are pulled by the microtubules of the mitotic spindle during anaphase, they appear V-shaped because the centromeres lead the way, dragging the trailing arms of the chromosomes toward the pole.
  • telophase: begins after chromosomal movement stops.. The identical sets of chromosomes, now at opposite poles of the cell uncoil and revert to the threadlike chromatin form. A nuclear envelope forms around each chromatin mass, nucleoli reappear in the identical nuclei, and the mitotic spindle breaks up.
55
Q

What is scytokenisis?

A

division of a cell’s cytoplasm and organelles into two identical cells

56
Q

what is the cleavage furrow

A

a slight indentation of the plasma membrane

57
Q

describe meiosis 1 and the 4 phases it consists of.

A

meiosis I: begins once chromosomal replication is complete, consists of four phases: prophase I, metaphase I,anaphase I, and telophase I.

  • Prophase I is an extended phase in which the chromosomes shorten and thicken, the nuclear envelope and nucleoli disappear, and the mitotic spindle forms. First, the two sister chromatids of each pair of homologous chromosomes pair off, an event called synapsis. The resulting four chromatids form a structure called a tetrad. Second, parts of the chromatids of two homologous chromosomes may be exchanged with one another. Such an exchange between parts of nonsister (genetically different) chromatids is called crossing-over. This process, among others, permits an exchange of genes between chromatids of homologous chromosomes.
  • In metaphase I, the tetrads formed by the homologous pairs of chromosomes line up along the metaphase plate of the cell, with homologous chromosomes side by side.
  • During anaphase I, the members of each homologous pair of chromosomes separate as they are pulled to opposite poles of the cell by the microtubules attached to the centromeres. The paired chromatids, held by a centromere, remain together. (Re- call that during mitotic anaphase, the centromeres split and the sister chromatids separate.)
  • Telophase I and cytokinesis of meiosis are similar to telophase and cytokinesis of mitosis. The net effect of meiosis I is that each resulting cell contains the haploid number of chromosomes because it contains only one member of each pair of the homologous chromosomes present in the starting cell.
58
Q

Describe meisis II and it’s 4 stages.

A

meiosis II: The second stage of meiosis, meiosis II, also consists of four phases: prophase II, metaphase II, anaphase II, and telophase II. These phases are similar to those that occur during mitosis; the centromeres split, and the sister chromatids separate and move toward opposite poles of the cell.

59
Q

What is cancer?

A

: is a group of diseases characterized by uncontrolled or abnormal cell division. When cells in a part of the body divide without control, the excess tissue that develops is called a tumor or neoplasm

Biology 235 (14 decks)

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