chapter 5-cellular biology Flashcards
what is the cell theory
1) all living things are composed of cells
2) the cell is the basic functional unit of life
3) the chemical reactions of life take place inside the cell
4) cells arise only from pre-existing cells
5) cells carry genetic information in the form of DNA. this genetic material is passed from parent cell to daughter cell
what are the 6 kingdoms
1) bacteria
2) Archaea
3) Protista
4) Fungi
5) Plantae
6) Animalia
Cell membrane function
1) encloses the cell and exhibits selective permeability
2) regulates the passage of materials into and out of the cell
3) consists of a phospholipid bilayer with proteins embedded throughout.
fluid mosaic model
- cell membrane consists of a phospholipid bilayer with proteins embedded throughout.
- The lipids and many of the proteins can move freely within the membrane
structure of phospholipid
- long, nonpolar, hydrophobic, fatty chains of carbon and hydrogen face each other
- phosphorus containing, polar, hydrophobic heads facing outwards
what kind of structures are readily permeable in the plasma membrane
- small, hydrophobic, non polar
AND - small polar
What kind of particles cross the membrane though protein channels
small charged particles
what kind of particles cross the membrane through carrier proteins
charged ions and larger charged mc
what are the dense structures in the nucleus and what occurs there
nucleolus and rRNA is synthesized
what are histones and how does DNA complex with it during DNA replication and transcription
- histones are structural proteins with DNA wound around it
- DNA replication: DNA tightly winds around the histone compacting chromatin into chromosome
- transcription: DNA unwinds itself from the histone to allow transcription to occur
what is chromatin
loose DNA
nucleoid
in prokaryotes
- contains the circular chromosomes
what is the role of ribosomes and what are they made of
- role: protein production
- 2 rRNA sequences called ribosomal subunits
in Eukaryotes where are ribosomes synthesized and function
synthesized in the nucleolus and function in cytoplasm
in prokaryotes where are ribosomes synthesized and function
synthesized and function in cytoplasm
what is the ER
is a network of membrane-enclosed spaces involved in the transport of materials throughout the cell particularly those materials designed to be secreted by the cell
role of Rough ER
contains ribosomes and plays an important roll in the production of proteins
role of Smooth ER
involved with metabolism and production of lipids
role of golgi
-Receives vesicles and their contents from the smooth ER and then modifies them (ex. glycosylation), repackages them into vesicles and distributes the to the cell surface for exocytosis
Role of mitochondria
site of aerobic respiration within the cell, responsible for the conversion of sugars, fats, and other sources of fuel into usable energy ( specifically ATP)
-Contains its own genome ( which resembles cellular bacterial chromosomes)
structure of mitochondria
- Outer membrane: fomrs barrier with the cytosol
- Inner membrane: is folded into cristae and contains enzymes for the ETC
- Intermembrane space ( between the 2 membranes
- Matrix: within the inner membrane: contains the genome
how does the mitochondria DNA divide
binary fission
where does the cells metabolic activity occur
in the cytoplasms
by what does transport within the cells cytoplasm occur
cyclosis: streaming movement within the cell
what are Vacuoles and Vesicles and their role
membrane bound sacs involved in the transport and storage of materials that are ingested secreted processed or digested by the cell
centrioles
composed of MT and are involved in spindle organization during cell division
- Not membrane bound
- Animal cells have a pair of centrioles oriented at R angles to each other that lie in a region of the cell called the centrosome
- Plant cells do not have centrioles
what is a centrosome
organizes MT and helps regulate the progression of the cell cycle
function of lysosomes
membrane bound vesicles that break down material ingested by the cell
- contain hydrolytic enzymes
An injured cell or dying cell may self-destruct by rupturing the lysosome membrane and releasing its hydrolytic enzymes called
autolysis
function of cytoskeleton
supports the cell, maintains its shape and aids in cell motility
what is the cytoskeleton composed of
MT, microfilaments, intermediate filaments
what are microtubules
- hallow rods made up of polymerized tubulin that radiate throughout the fell and provide it with support
- They provide a framework for organelle movement within the cell
what are centriole function and what are they composed of
- they direct the separation of chromosomes during cell division
- composed of MT
what are cilia and flagella
they are specialized arrangements of MT that extend from certain cells and are involved in cell memory and cytoplasmic movement
what are Microfilaments
are solid rods of actin which are important in cell movement as well as support
- Move materials across the PM
what kind of proteins are intermediate filaments + ex
diverse group of filament proteins ex keratin
function of intermediate filament
structural backbone of the cell as they are able to withstand a tremendous amount of tension ( make cell structure more rigid) AND
help anchor organelles to their respective place in the cell
what is simple diffusion
is the net movement of dissolved particles down their concentration gradient (high to lower [ ])
- passive process
what is osmosis
simple diffusion of water from lower solute [ ] to a region of higher solute [ ]
what is a hypertonic medium to the cell and what occurs
the medium outside the cell has higher solute [ ] and water flows out
- plasmolysis occurs
what is plasmolysis
shrivelling of the cell
what is a hypotonic medium to the cell and what occurs
when the extracellular environment is less concentrated than the cytoplasm of the cell and water flows into the cell
- the cell lyse (bursts)
what is when a cell is isotonic to the environment and what happens
when the extracellular environment has the same concentration of solutes as the cell cytoplasm
- water flows back and forth in equal amounts across the cell membrane
during osmosis water moves towards___equilibrium
isotonic
what is facilitated diffusion
the net movement of dissolved particles down their concentration gradient through special channels or carrier proteins in the cell membrane
- no energy required
what is active transport
- the net movement of dissolved particles against their [ ] gradient with the help of transport proteins
- requires energy
what are the carrier proteins
- Symporters: move 2 or more ions or mc in the same direction across the membrane
- Antiporters: exchange one or more ions ( or mc) for another ion or mc acorss the membrane
- Pumps: energy-dependent carriers ( require ATP) ex Na/K pump
what is endocytosis
a process in which the cell membrane invaginates, forming a vesicel that contains extracellular medium
-allows the cell to bring large volumes of extracellular material inside the cell
types of endocytosis
- pinocytosis: ingestion of fluids or small particles
- phagocytosis: engulfing of large particles (particles may bind to receptors on the cell membrane, triggering endocytosis)
what is exocytosis
- a vesicle within the cell fuses with the cell membrane and releases a large volume of content to the outside
- fusion of the vesicle with the cell membrane can play an important role in cell growth and intercellular signaling ex. NT that act as signals to neighboring cells
what is cell division
: cell doubles its organelles and cytoplasm, replicates its DNA and divides in 2
what is the period of growth and chromosome replication in cell cycle
interphase
how long does a cell spend in interphase
90% of its life
after replication the chromosome consists of 2 identical sister chromatids held together by what
a central regions called centromere
how does the DNA appear during interphase
individual chromosomes are not visible but the DNA is uncoiled and called chromatin
what are the 3 parts of interphase
1) G1: initiation of interphase
- active growth phase, cell size increase and synthesizes of proteins occurs
- varies in size
2) S: DNA synthesis
3) G2: cell prepares to divide, grows and synthesizes proteins
what type of cells go through mitosis
somatic cells
what is mitosis
division and distribution of the cells DNA to its 2 daughter cells such that eachc ell receives a complete copy of the original genome
what is karyokinesis
nuclear division
what is cytokinesis
cell division
what occurs in prophase
- cell prepares for karyokinesis
1) chromatin is condensed into chromosomes
2) nuclear membrane dissolves
3) centriole pairs separate and move towards opposite poles of the cells
what occurs in metaphase
1) centrioles are at opposite poles and form spindle fibres to anchor themselves
2) more spindle fibres radiate outwards and attach to each chromatid at the kinetochore
3) the spindle finer aligns the chromosome along the metaphase plate
what is a kinetochore
a protein located on the centromere of the chromosome
what occurs during anaphase
1) centromeres split so that ach chromatid has its own distinct centromere
2) sister chromatids are pulled towards opposite poles by shortening of the spindle fibers
3) separation of sister chromatid of each chromosome
what occurs during telophase
1) spindle apparatus disappears
2) a nuclear membrane forms around each set of newly formed chromosomes
3) each nucleus contains the same # of chromosomes ( diploid number) as the original nucleus
4) chromosomes uncoil, resuming their interphase form
5) towards the end: cytoplasm divides into 2 daughter cells each with a complete nucleus and its own set of organelles
what occurs during cytokinesis
1) animal cells: cleavage furrow forms: cell membrane indents along the equator of the cell and separates into 2 nuclei
2) plant cells: cell plate forms between the 2 nuclei splitting the plant in half and allows the cell to divide
how is mitosis different than meiosis
2 parents are involved (fusion of 2 gametes) and it produces haploid number instead of preserving its diploid number
what is meiosis
the process by which these sex cells are produced
what are sex cells
gametes
what is ploidy
how many chromosomes an organism has in a homologous set
what is a homologous set
chromosomes that share structure and gene location but can have different alleles
what does the first meiotic division yield
2 haploid daughter cells ( separates the pair of homologues chromosomes ( not chromatids)
what occurs during prophase 1
1) chromatin condenses into chromosomes
2) spindle apparatus forms
3) nucleoli/nuclear membrane disappears
4) crossing over occurs: the genetic exchange between chromatids of homologous chromosomes and its vital for a species as it increases genetic diversity
crossing over steps
1) homologous chromosomes come together and intertwine called synapsis forming a tetrad ( 4 sister chromatids)
- where the sister chromatids interact is called chiasmata
2) once synapsis begins chromatids of homologues chromosomes break at corresponding point and exchange equivalent pieces of DNA
what is the process synapsis
meiosis 1
- homologous chromosomes come together and intertwine
what occurs during metaphase 1
-homologous pairs ( tetrads) align at the equatorial plane and each pair attaches to a separate spindle fiber at the kinetochore
what occurs during anaphase 1
1) homologous pairs separate and are pulled to opposite poles of the cell called disjunction (accounts for the Medelian law of segregation)
2) during disjunction: each chromosome of paternal orgin separates ( or disjoins) from its homologue of maternal origin and their chromosomes end up in either daughter cell
3) each daughter cell will have a unique pool of genes from a random mixture of maternal and paternal origin
what is nondisjunction and when does it occur
when cells don’t separate appropriately during meiosis resulting in the daughter cell having an incorrect number of chromosomes
- anaphase 1
what occurs using telophase 1
1) Nuclear membrane forms around each new nucleus thereby forming 2 haploid cells in which each chromosome has 2 sister chromatids these cells are intermediate daughter cells
similarities and differences between the second meiotic division and mitosis
similar to mitosis bc sister chromatids are separated BUT meiosis both parent (intermediate daughter cells) and daughter cells are haploid not diploid
what occurs during prophase 2
1) Nuclear envelope dissolves
2) nucleoli disappear
3) the centrioles migrate to opposite poles
4) spindle apparatus begins to form
what occurs during metaphase 2
Chromosomes line up on the metaphase plate
what occurs during anaphase 2
1) Sister chromatids of the chromosomes are separated and are pulled apart by shortening spindle fibers
2) Each separated sister chromatid is now considered a chromosome itself
what occurs during telophase 2
1) Nuclear envelope forms around each new set of chromosomes
2) Cytokinesis follows and 2 haploid daughter cells are formed per intermediate daughter cells= completion of meiosis 2
how many daughter cells are produced per gametocyte
up to 4 haploid daughter cells
