cells Flashcards
function of the nucleus
- the genetic control center of cellular activity
function of the endoplasmic reticulum
ER synthesises steroids and other lipids, detoxifies alchohol and other drugs and manufactuers all membranes of the cell
rough ER
- produces phospholipids and proteins of the plasma membrane nd synthersizes proteins that are either packaged in organelles such as lysomomes or secreted from the cell
smooth ER
- detoxifies and proliferates drugs
ribosomes
- read coded messages
- assemble amino acids into proteins specified by the code
- attach to rough ER when they make proteins
golgi complex
- recieves and modifies newly syntherzied polypeptides, syntherzies CHO, adds CHO to gycoproteins and packages cell products into golgi vesicals
golgi vesicals
- becomes secretory vesicals and carry cell products to apical surface for exocytosis or become lysomes
lysosomes
contain enzymes for intracelluar digestion, autophagy, programmed cell death and glucose mobilization
mitochondria
ATP synthesis
centrioles
form mitotic spindle during cell division; unpaired centrioles form basal bodies of cilia and flagella
microvilli
increase absorpitive surface area; widespread sensory roles
flagellum
sperm motility
cilia
move substances along cell surface
microtubules
enable motility of cell parts
plasma membrane
it defines the boundries of the cell, governs its interactions with other cells, and controls the passage of materials into and out of the cell
membrane proteins
- integral proteins
- transmembrane proteins
- peripheral proteins
functions of membrane proteins
- receptors
- second messenger systems
- channel proteins
- enzyme
- gated channel
- cell adhesion molecules
- cell identity markers
filtration
movement of material without the aid of a carrier protein
simple diffusion
movement of water and solutes through a selectivley permerable membrane as a result of a different gradient
osmosis
net flow worth of water through a selectivley permable membrane driven by either a difference in solute concentration or a mechanical force
facilitated diffusion
transport of particlas through a selectivley permeable membrane down their concnetration gradient by a carrier that does not directly consume ATP
active transport
transport of particlas through a selectivley permeable membrane up their concnetration gradient by a carrier that does consume ATP
endocytosis
vesicular transport of particals into a cell
exocytosis
process of eliminating material from the cell
protein synthesis
when a gene is activated a MRNA is made of the gene. the MRNA migrates from the nucleus to the cytoplasm where is serves as a code for assembling amino acids in a particular order to make a protein
transcription
RNA polyermarse binds to the DNA and assembles the RNA. it reads the base sequences from DNA and makes a corresponding RNA.
translation
3 steps: 1- initiation 2- enlongation 3- termination 4- making proteins for packaging or export
initiation
mRNA passes through a nucelar pore into the cytosol and forms a loop. A ribsome binds to the subunit and slides along the mRNA until it finds a start codon (AUG). the initiator tRNA with the matching anticodon pairs with the start codon embraces the mRNA groove reading its bases.
elongation
the next tRNA arrives and binds with the A site of the ribosome and continues to make a chain of amino acids as the ribosomes slide along the bases reading the code.
termination
when the ribosome reaches the stop condon its A site binds a protein called a release factor instead of tRNA. The release factors causes the finished protein to break away from the ribosome and go off into the cytsol. The ribsome then dissociates into its two subunits
making proteins for packaging ir export
is a protein is to be packaged into a lysosome or secreted from the cell the ribosome docks onto the rough endplasmic reticulum. The ER modifies this protein and packages it into transport vesicles.
G1 (first gap phase)
- cell synthesizes proteins, grows and carries out preordained tasks for the body
- accumalte materials needed to replicate DNA
synthesis phase
in which the cell makes a dupilcate copy of the centrioles and all of its nuclear DNA. The two identical sets of DNA molecules are then available to be divided up between daughter cells at the next cell divison
G2 phase
- cell growth, makes more organelles, finishes replicating centrioles, and synthesizes rzes enzymes that control cell division
M miotic phase
cell replicates its nucleus and then pinches in two form two new daughter cells
mitosis functions
- development of an individual
- growth of tissues and organs
- replacement of cells that die
- repair of damaged tissues
prophase
chromsomes condense and nucelar envelope breaks down. Spindle fibre grows from centrioles, centrioels migrate to opposite poles of cell
metaphase
chromosomes lie along midline of cell. Long microtubules reach out from each centriole to the chromsomes and shorten.
anaphase
centromeres divide into 2. Spindel fibres pull sister chromatides to opposite poles of cells.
telophase
chromsomes gather at each pole of cell. Chromatin decondenses. New nuclear envelope appears at each pole. new nuceoli appear in each nucleus. Miotic spindel vanishes.
DNA structure
is a long threadlike molecule with diameter of 2nm.
- double helix composed of a back bone os phosphate groups alternating with the sugar deoxyribose
- DNA is a polymer of nucleotides which consists of sugar and a phosphate group
Chromosome structure
DNA is complexed with proteins called chromatin which occurs as long filaments called chromosomes
differene between RNA and DNA
DNA - deoxyribose - ATCG - 2 double helix - functions in nucleas cannot leave - codes for synthesis of RNA and protein RNA - ribose - one - leaves nucleas functions mainly in cytoplasm - carries out the instructions in DNA assembles proteins
