Chapter 3 Flashcards
Cells
What are the smallest unit of life?
Cells
4 parts of a cell:
Plasma membrane
Cytoplasm
Nucleus
Cytosol
-Double layer of phospholipids with embedded proteins
-Separates outside of cell from inside of cell
-Controls what is passed through cell
-Active barrier separating intracellular fluid from extracellular material
Plasma membrane
Substance that acts as glue to hold cells together
Extracellular matrix
Cellular secretions
Extracellular fluids
What are plasma membrane functions?
-Mechanical barrier
-Selective permeability
-Electrochemical gradient
-Communication/Cell recognition
-Cell signaling
What are the components of the plasma membrane?
Phospholipid bilayer
Integral membrane proteins
Peripheral membrane proteins
Glycocalyx
Lipid Bilayer
75% phospholipids
5% glycolipids
20% cholesterol
-Firmly inserted into membrane
-Hydrophobic and hydrophilic regions
-Functions: transport proteins, receptors, enzymes
Integral membrane proteins
-Loosely attached to integral proteins
-Include filaments on intracellular surface used for plasma membrane support
Peripheral membrane proteins
Glycocalyx
-Consist of carbohydrates sticking out of cell surface
-Glycolipids and glycoproteins
What are three ways that cells are bound together?
Tight junctions
Desmosomes
Gap junctions
Tight junctions
Impermeable junctions that form continuous seals around the cells and prevent molecules from passing through intercellular space
Desmosomes
Anchoring junctions that bind adjacent cells together and act like molecular “velcro”
Gap junctions
Communicating junctions that allow ions and small molecules to pass
Particularily important for communication in heart cells and embryonic cells
Cytoplasm
-All cellular material is located between plasma membrane and nucleus
-Cytosol, Inclusions, Organelles
Cytosol
Gel-like solution made of water and soluble molecules such as proteins, salts, sugars, etc.
Mitochondria
Site of ATP synthesis, powerhouse of cell
Sites of protein synthesis
Ribosomes
Sugar groups are attached to proteins within the cistems
Proteins are bound in vesicles for transport to Golgi apparatus and other sites
External face synthesizes phospholipids
Rough endoplasmic reticulum
Membranous system of sacs and tubules; free of ribosomes
Site of lipid and steroid (cholesterol) synthesis, lipid metabolism, drug detoxification, calcium storage
Smooth ER
A stack of flattened membranes and is associated with vesicles close to the nucleus
Packages, modifies, and segregates proteins for secretion from cell
Golgi apparatus
Membranous sacs containing catalase and oxidase enzymes
Detoxify substances
Peroxisomes
Breaks down hydrogen peroxide
Catalase
Membranous sacs containing acid hydrolases
Sites of intracellular digestion and recycling
Lysosomes
Cylindrical structures made of tubulin proteins
Support the cell and give it shape; involved in intracellular and cellular movements
Form centrioles, cilia, flagella, if present
Microtubules
Protein fibers; composition varies
Stable cytoskeletal elements; resist mechanical forces acting on the cell
Intermediate filaments
Fine filaments composed of protein actin
Involved in muscle contraction and other types of intracellular movement
Helps form the cell’s cytoskelton
Microfilaments
Varied; includes stored nutrients such as lipid droplets and glycogen granules, protein crystals, pigment granules
Storage for nutrients, wastes, and cell products
Inclusions
What are three cellular extensions?
Cilia
Microvilli
Flagellum
Short cell surface projections, each cilium contains of nine pairs of microtubules surrounding a central pair
Coordinated movement creates a unidirectional current that propels substances
Cilia
Like cilium, but longer; only example in humans is sperm tail
Propels the cell
Flagellum
Tubular extensions of the plasma membrane; contain a bundle of actin filaments
Increase surface area of absorption
Microvilli
Nuclear envelope
Nucleolus
Chromatin
Parts of the nucleus are…
Houses DNA
Contains the genetic library of blueprints for synthesis of nearly all cellular proteins
Nucleus
Folds inside of of mitochondria
Cristae
Double membrane barrier, outer layer is continuous with rough ER, inner layer is a network mesh of proteins that maintains nuclear shape
Nuclear envelope
Allow substances to pass into and out of nucleus
Nuclear pores
Site of ribosomal subunit manufacture
Nucleolus
Consists of histone proteins, DNA, and RNA
Arranged in fundamental units called nucleosomes
Chromatin
Consist of DNA wrapped around a histone
Nucleosomes
Paired cylindrical bodies, each composed of nine triplets of microtubules
Organize microtubule network
Form spindle and asters
Form bases of cilia and flagellum
Centrioles
Contain genes, condensed chromatin
Chromosomes
Series of changes a cell undergoes from the time it is formed until it reproduces
Major periods - interphase, mitotic phase
Cell Cycle
Cell carries out its routine activities and prepares for cell division
Nuclear material is in uncondensed chromatin state
Interphase
G1- vigorous growth
S - DNA replication
G2 - division preparation
What are the three phases of interphase?
Division of the cell occurs, consists of two distinct events
1) Mitosis
2) Cytokinesis
M (Mitotic) phase
Division of the nucleus, in which duplicated DNA is distributed to new daughter cells
Mitosis
Begins in late anaphase and continues through and beyond telophase
Ring of actin microfilaments contracts to form a cleavage furrow
Two daughter cells are pinche apart
Cytokinesis
