Week 1 Textbook Flashcards
what are cells
small membrane-enclosed units filled with concentrated aqueous solution of chemicals
- they can create copies of themselves by growing and dividing into two
- they are the simplest forms of life
paramecium is covered with thousands of __
cilia
how do multicellular organisms function in their roles
division of labour among cells - allowing some cells to become specialized to an extreme degree for particular tasks
molecularly, how do cells split DNA to give to each new emerging cell
DNA replication
RNA transcription
Protein synthesis translation
What is DNA
double-stranded polynucleotide formed from 2 separate chains of deoxyribonucleotides that are bonded covalently cells storage of genetic material that is transmitted gen to gen
what is RNA
a single-stranded molecule produced by the transcription of DNAmade by covalently linking ribonucleotide subunits some RNA molecules have their own regulatory structural or chemical activities but most of them are translated into different polymers like proteins
what is the central dogma
the flow of info from DNA to RNA to Protein is so fundamental to life it is referred to the central dogma everything is surrounded and based off of this process
what is a protein
macromolecule built from amino acids that provide cells with their shape and structure and perform most of their activities they are built from all 20 AA - but all the AA are linked in different sequences giving each molecule a different three-dimensional shape or conformation.
what does it mean by saying life is an autocatalytic process
DNA and RNA provide the sequence information to make proteins and allow them to copy themselves but the proteins when made provide catalytic activity needed to continue the feedback loop - shows the self-reproducing behaviour of living things
{{c1::viruses}} cannot reproduce by their efforts
instead, they use a parasite to invade and make copies of themselveswithout a host cell, the viruses are inert and are not considered to be living
what are mutations
When a cell replicates its DNA in preparation for cell division, sometimes errors can occur that cause the daughter cells to be different. This can change the offspring for the better, for the worse, or for the neutral.
what are the three major divisions or domains of life
eukaryotes, bacteria, archaea
what is a eukaryote
has a nucleus
store DNA in a membrane-enclosed organelle called the nucleus
larger
large genome
what is a prokaryote
lacking a nucleus
not as complex
smaller
define bacteria
generally small, invisible to the eye, rod-like, spherical, corkscrew-shape + tough protective coat or cell wall surrounding the plasma membrane that encloses a cell with cytoplasm and DNA
E. coli - used as a model organism some are aerobic and some are anaerobic some can live in totally inorganic substances and get their necessary elements from the atmosphere some bacteria use photosynthesis or derive energy from chemical reactions
give examples of how bacteria can be useful
bacteria can be on our skin or in your gut to promote a healthy immune response organelles such as the mitochondria and chloroplast have evolved from aerobic bacteria
T/F bacteria, under optimal conditions, can reproduce very quickly
true, this causes the rapid ability for the bacteria to use a new food source, survive in tough conditions or be resist to a new antibiotic
what type of environment does archaea live in
a division of prokaryotes that live in hostile environments such as hot springs or concentrated brine
explain the importance of archaea
predominant form of life in soil and seawater, they play a major role in recycling nitrogen and carbon - the two most important elements for the biology of cells
they live in hostile environments because as the earth was developing those conditions played out which show how they first evolved.
T/F archaea resemble bacteria physically, but genetically they are more closely related to eukaryotes
true
eukaryotes come from the ancestral cell of archaea this started the evolution of the eukaryotic lineage
T/F yeasts are free-living eukaryotes
true
explain the nucleus
enclosed with 2 membranes that form the nuclear envelope contains DNA - codes of genetic information - a long chain of polymers –> chromosomesmitosis/cell division occurs inside
what is the definition of a chromosome
long threadlike structure composed of DNA and proteins that carry the genetic information - they become visible as a distinct entity when the cell is ready to divide
explain the structure and function of the mitochondria
structure
in eukaryotic cells, in cytoplasm and enclosed by 2 separate membranes (inner folds into the interior organelle)smooth outer membrane layer inner membrane contains most of the proteins responsible for energy production in eukaryotic cells - folded up = high SA they’re strong resemblance to modern-day bacteria = evidence of evolution from an aerobic bacterium + symbiosis of metabolic support while being engulfed by an anaerobic ancestor of eukaryotic cell
function
generators of the chemical energy for the cell take energy from the oxidation of food molecules (sugars) to produce ATP
- consumes O2 and releases CO2 = cellular respiration (breathing)
- contains their own separate DNA and reproduce by cell division
how was the function discovered?
- opening cells, spinning in the centrifuge and organizing separated parts according to their size and density
explain the structure and function of chloroplasts
structure
- large green organelles that are found in plants and algae contains their own DNA and uses cell division to grow/reproduce said to have evolved from photosynthetic bacteria that was living inside a eukaryote already with a mitochondria
- more complex than mitochondria in structure
- they have 2 surrounding membranes + internal stacks of membranes containing green pigment - chlorophyll = photosynthesis
function
- photosynthesis - chloroplast traps the energy of sunlight to create sugar molecules - plant cells can extract this stored energy when needed by oxidizing the sugar
- a by-product = oxygen
- enable plants to get energy from sunlight to produce food molecules + oxygen that the mitochondria use to generate chemical energy in the form of ATP
Explain the structure and function of the endoplasmic reticulum
structure
- irregular maze of interconnected spaces enclosed by a membrane
function
- the site where most of the cell components are made to be exported from the cell good for cells that are specialized to secrete large amounts of protein
explain the structure and function of the Golgi apparatus
structure
- stacks of flattened sacs that are enclosed by membranes
function
- modifies and packages molecules made in the ER that are destined to be either secreted from the cell or transported to another cell compartment
explain the structure and function of lysosomes
structure
- small, irregularly shaped organelles
function
- intracellular digestion occurs - releasing nutrients from ingested food particles into the cytosol/cytoplasm and breaking down unwanted molecules for recycling or excretion from the cell
explain the structure and function of peroxisomes
structure
- small, membrane-enclosed vesicles
function
- provide a sequestered environment for a variety of rxns in which hydrogen peroxide is used to inactivate toxic molecules
what are endosomes
imported materials are grouped to form an endosome - a membrane-encoded organelle (when they are being delivered by endocytosis)
compare endocytosis and exocytosis
endocytosis
- across the plasma membrane, they import extracellular materials by endocystosis by using small membrane-bound
endosomes
exocytosis
- the cell secretes intracellular materials by exocytosis via endsomes
- most of the hormones and signal molecules that allow cells to communicate with each other = exocytosis
explain the structure and function of the cytosol
structure
- the cytosol is part of the cytoplasm that is not contained within intracellular membranes largest compartment water-based gel than a liquid solution because it holds large and small molecules close together
functions
- its of many chemical reactions that are fundamental to the cell’s existence
- breakdown of nutrient molecules takes place in the cytosol
explain the structure and function of the cytoskeleton
structure
- a system of long fine crisscrossed filaments in the cytoplasm of a eukaryotic cell
- the cytoskeleton is continually assembling, disassembling
function
- gives the cell shape and capacity for directed movement
- composed of 3 major filaments (actin filament, microtubules, intermediate filaments)
- gives the cell its mechanical strength, controls shape, guides and directs movements
- in plant cells - chloroplasts and mitochondria move along cytoskeletal tracks = cytoplasmic streaming - the rate of streaming it affected by light, temp, pH
explain the 3 major types of filament
actin filaments
- thinnest + very abundant and used a lot inside muscle cells = central part of machinery responsible for muscle contraction used in amoeba to crawl around using actin polymerization - growing actin filaments push out pseudopods (feet) - organelles also move with it on cytoskeletal tracts
microtubules
- thickest + hollow tubes - in dividing cells they become reorganized into an array that helps pull the homologous chromosomes apart and distribute them evenly between the 2 new daughter cells being made
intermediate filaments
- medium thickness + strengthens animal cells overall the 3 types work together to make a system of ropes, motors and girders for the cell
what are motor proteins
they used the energy stored in molecules of ATP to trundle along these tracks and cables + carry organelles and proteins throughout the cytoplasm
what is a fibroblast
a cell that inhabits connective tissue and deposits extracellular matrix
ex: animal cell