Physiology Chapter 2B: Cell Structure And Function

Front 1

Differentiation (4)

Back 1

-More than 100 trillion cells in human body
-All derived from fertilized ovum
-200 different types (four general categories)
-Undergo differentiation during development

Front 2

Plasma membrane

Back 2

Barrier between cell and external environment

Front 3

Fluid inside cell

Back 3

intracellular fluid (ICF)

Front 4

Fluid outside cell

Back 4

extracellular fluid (ECF)

Front 5

Internal compartments of cell (4)

Back 5

-Nucleus
-Cytoplasm
-Cytosol
-Organelles

Front 6

Structure of the Plasma Membrane (4)

Back 6

Fluid mosaic model
-Phospholipid bilayer
-Membrane proteins
-Membrane carbohydrates

Front 7

Phospholipids (3)

Back 7

-Basic structure of membrane
-Barrier to passage of water-soluble substances between ICF and ECF
-Provides fluidity to membrane

Front 8

Cholesterol (4)

Back 8

-Adds fluidity to membrane
-Interferes with hydrophobic interactions between phospholipids
-Prevents crystallization of phospholipid
-Decreases permeability of membrane to water

Front 9

Membrane Proteins (2)

Back 9

-Some are transmembrane proteins
-Channels
-Carrier proteins
-Some are located on one side of membrane
-Enzymes
-Receptors
-Part of cytoskeleton

Front 10

Blood Type - Part of cell identity

Back 10

-ABO system of blood type
-Blood Type A = sugar group shape A
-Blood Type B =sugar group shape B
-Blood type AB=sugar groups of both types
-Blood type O = no sugar group A or B

Front 11

Membrane Carbohydrates (structure & function)

Back 11

-Carbohydrates covalently bound to membrane lipids or proteins
-Glycolipids
-Glycoproteins
-Functions
-Glycocalyx
-Cell recognition

Front 12

Structure and Function of the Nucleus (6)

Back 12

-Structure
-Nuclear envelope
-Nuclear pores
-Nucleolus—site of rRNA synthesis
-Function
-Transmission and expression of genetic information
-Contains DNA—stores genetic code
-DNA transcribed to RNA—necessary to express code

Front 13

Cytoplasm

Back 13

Cytosol and organelles

Front 14

Functions of cytosol (fluid of the cell) (3)

Back 14

-Location of specific chemical reactions
-Storage of fat, carbohydrates as inclusions
-Storage of secretory vesicles

Front 15

Endoplasmic Reticulum (ER) - Rough ER, Smooth ER (5)

Back 15

-Rough ER
-Flattened sacs
-Granular appearance
-Smooth ER
-Tubules
-Smooth appearance
-Lumens of the two ERs are continuous

Front 16

Functions Rough Endoplasmic Reticulum (3)

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-Functions in synthesis of proteins to be packaged into vesicles
-Exported out of cell
-Incorporated into plasma membrane

Front 17

Functions Smooth Endoplasmic Reticulum (3)

Back 17

-Functions in lipid synthesis, including triglycerides and steroids
-Stores calcium
-Specialized in some cells
Example: Liver smooth ER contains detoxification enzymes

Front 18

Golgi Apparatus Functions (2)

Back 18

-Functions
-Post-translational processing of proteins
-Packaging of proteins (and other molecules) into vesicles and directing them to target

Front 19

Mitochondria (4)

Back 19

-Are energy-producing organelles (ATP)
-Involved in aerobic respiration
-How we get energy from food molecules
-This is why we breathe

Front 20

Lysosomes Function (4)

Back 20

-Function
-Contain enzymes that degrade cellular or extracellular debris
-To degrade extracellular debris
-Endocytosis
-Phagocytosis

Front 21

Peroxisomes (7)

Back 21

-Are vesicles containing enzymes
-More specific than Lysosomes
-Involved in some of the detoxification in liver
-Toxin breakdown may produce H2O2
-Catalase – an enzyme present in Peroxisomes
-Converts H2O2 to H2O and O2
-ALD (adrenoleukodystrophy) – lack of enzyme used to breakdown some lipids

Front 22

Ribosomes (4)

Back 22

-Ribosomes = rRNA and proteins
-Important in protein synthesis
-Fixed
-Attached to endoplasmic reticulum
-Free
-Loose in cytosol

Front 23

Centrioles (3)

Back 23

-Paired cylindrical structures
-Perpendicular to each other
-Function in development of mitotic spindle (mitosis)

Front 24

Cytoskeleton (7)

Back 24

Lattice of fibrous proteins

Functions of cytoskeleton
-Mechanical support and structure
-Intracellular transport of materials
-Suspension of organelles
-Formation of adhesions with other cells
-Contraction
-Movement

Front 25

Protein Synthesis (3)

Back 25

-The role of the genetic code
-Transcription
-Translation

Front 26

Steps of Protein Synthesis (4)

Back 26

-Code for proteins
-Genetic code
-transcribed in nucleus to mRNA
-mRNA moves from nucleus to cytoplasm
-mRNA translated in cytoplasm to proteins

Front 27

Genetic Code (7)

Back 27

-Code for 20 amino acids
-Triplet and codon
-Three base sequence
-Four bases
-43 = 64 codons
-Each codon codes for one amino acid
Example
CCC  proline
-One amino acid can be coded by more than one codon
Example
CCC  proline
CCG  proline

Front 28

Translation

Back 28

-Requires mRNA, tRNA, and rRNA (ribosomes)
-Occurs in cytoplasm at the ribosome

Front 29

Cell Division

Back 29

-Most cells have limited life span
-Types of cell division
-Mitosis
-Meiosis
-Mitosis replaces cells

Front 30

Most cells of body are in interphase-

Back 30

the non-dividing stage of life cycle

Front 31

Interphase is subdivided into: (3)

Back 31

-G1 - cell performs normal physiological roles
-S - DNA is replicated in preparation for division
-G2 - chromatin condenses prior to division

Front 32

Mitosis (4)

Back 32

-Is phase of life cycle when cell divides
-Chromosomes are condensed & duplicated
-Consist of 2 duplicate strands called chromatids
-Which are connected at the centromere

Front 33

Mitosis Mitosis Consists of 4 stages:

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-prophase, metaphase, anaphase, telophase
-Sometimes Prometaphase as well - text

Front 34

prophase

Back 34

In prophase chromosomes become visible distinct structures
Chromosomes condense, become visible. Spindle apparatus forms.

Front 35

metaphase

Back 35

In metaphase chromosomes line up single file along equator

Front 36

anaphase (2)

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-In anaphase centromeres split
-Spindle fibers pull each chromatid to opposite poles
Sister chromatids separate to opposite poles of cell.

Front 37

telophase

Back 37

In telophase chromosomes condense and with completion of

Nuclear membranes assemble around
two daughter nuclei. Chromosomes decondense.
Spindle disappears.

Front 38

cytokinesis

Back 38

cytokinesis 2 daughter cells are produced
Division of the cytoplasm into two cells.

Front 39

G1, early interphase

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of daughter cells.
Cells resume normal functions or enter another division cycle.

Front 40

G2, Late interphase

Back 40

Cell checks for complete DNA replication.

Front 41

Mitotic Cell Division (5)

Back 41

-During Prophase, the Chromosomes Condense and the Spindle Microtubules Form and Attach to the Chromosomes
-During Metaphase, the Chromosomes Align Along the Equator of the Cell
-During Anaphase, Sister Chromatids Separate and Are Pulled to Opposite Poles of the Cell
-During Telophase, Nuclear Envelopes Form Around Both Groups of Chromosomes
-During Cytokinesis, the Cytoplasm Is Divided Between Two Daughter Cells

Front 42

Oncogenes

Back 42

Are genes whose mutations are associated with cancer

Front 43

Tumor suppressor genes (3)

Back 43

-Tumor suppressor genes inhibit cancer development
-E.g. gene p53 inhibits cells ability to divide
-Mutations in p53 are associated with cancer

Front 44

Telomeres (7)

Back 44

-Are non-coding regions of DNA at ends of chromosomes
-Each time a cell divides, a length of telomere is lost
-When telomere is used up, cell becomes senescent
-Believed to represent a molecular clock for aging
-Apoptosis occurs as a normal physiological response
-Also called programmed cell death
-Cancer cells can divide indefinitely – active telomerase

Front 45

Steps to cancer (5)

Back 45

-Damaged DNA
Including damaged p53 gene (p53 would stop cells with abnormal DNA from dividing)
-Abnormal cells signal for more blood vessels
-Immune System fails to recognize abnormally dividing cells
-Failure of contact Inhibition in abnormal cells
-Failure of CAMs (cell adhesion molecules) - cells no longer stick together - metastasis

Front 46

Steps to stopping cancer (2)

Back 46

-Treatments for metastasizing cancers include high-
energy radiation and chemotherapy with toxic drugs.
-These treatments target actively dividing cells.

Front 47

Possible future cancer treatments (3)

Back 47

- Repair or replace p53 gene

- Control/Stop angiogenesis

- Tag abnormal cells so immune system responds

Front 48

Meiosis (5)

Back 48

-Type of cell division occurring in ovaries & testes to produce gametes (ova & sperm)
-Has 2 divisions-DNA is replicated once & divided twice

-In 1st division homologous chromosomes pair along equator of cell rather than singly as in mitosis
-1 member of pair is pulled to each pole
-This gives each daughter cell 23 different chromosomes, consisting of 2 chromatids

-In 2nd division each daughter divides, chromosomes split into 2 chromatids
-1 goes to each new daughter cell
-Each daughter contains 23 chromosomes
-Rather than 46 like mother cell
-Meiosis is therefore called a reduction division

Front 49

Meiotic Cell Division

Back 49

-Meiosis Separates Homologous Chromosomes, Producing Haploid Daughter Nuclei
-Meiotic Cell Division Followed by Fusion of Gametes Keeps the Chromosome Number Constant from Generation to Generation
-Meiosis I Separates Homologous Chromosomes into Two Haploid Daughter Nuclei
-During Prophase I, Homologous Chromosomes Pair Up and Exchange DNA