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
what are protozoans
a free-living, nonphotosynthetic, single-celled motile eukaryote these cells may not live in extreme environments but they can have a variety of behaviours and appearances EX: didinium is a large carnivorous protozoan (eats other cells) structure: global shape with cilia at the top and bottom and snout at the top. function: uses beating and moving cilia to swim at high speeds, and when encountering another protozoan as prey they release paralyzing darts from its snout and opens up to ingest
T/F not all protozoans are predators
true
what are model organisms
studying a few representative species to gain a deeper understanding that could be achieved if they look at many different species
- lead to discoveries and benefits of human health
explain what we know about E.coli
“Anything found to be true about E. coli must also be true about elephants”
- small rod-shaped cell that lives in the gut of humans and other vertebrates - grows and reproduces in a simple nutrient broth in a lab
1. gene expression
2. how cells replicate their DNA and how they decode the instructions to make proteins
3. advances in biotechnology –> recombinant DNA
4. producing large quantities for therapeutic proteins - insulin = biomedicine
what are model organisms
a living thing selected for intensive study as a representative of a large group of species
- mouse, yeast, E.coli
scientists around the world can pool their knowledge and resources to gain a deeper understanding
- better to understand on than use many different species
explain E.coli
“Anything found to be true of E.coli must also be true of elephants”
- small, rod-shaped cells that live in the gut of the humans and other vertebrates
what has E.coli discovered as a model organism
- regulate gene expression
- how cells replicate their DNA to decode instructions –> proteins
- advancements in biotechnology
- recombinant DNA
- producing large quantities of therapeutic proteins = insulin
explain the structure of S. cerevisiae
small single-celled fungus
rigid cell wall, usually immobile, has an array of organelles (no chloroplast)
- when resources are available, it can grow a lot
- carries out the basic tasks of mating with the opposite sex - allows us to study the genetics of sexual reproduction
T/F fungi is more closely related to prokaryotes
false
it is more closely related to animals and eukaryotes
what can studying yeast help with?
understanding fundamental mechanisms in eukaryotic cells
- cell division
- chain of events by which the nucleus and all the other components of a cell are duplicated –> daughter cells
T/F bacteria and archaea are more closely related than animals and plants
false
bacteria and archaea are separated from each other by more than 3 billion years of evolution
- plants, animals, fungi diverged 1.5 b years ago
what plant have scientists chosen to study
a small weed in the cabbage family
- Arabidopis thaliana = model plant
- grown indoors, in large numbers, produces thousands of offspring
what has Arabidopis thaliana helped to understand?
the model organism has enabled us to understand
plants growing towards sunlight
flowering in the spring
coordinated development with the seasons
- studying this simple weed (has some similar genes in agricultural species) can provide insight on the development and physiology of the crop plants that we depend on
what has the nematode worm helped us with?
we now have a detailed description of the sequence of events
cells divide –> become specialized
- 70% of the genes have some counterparts in humans
- acts as a model for human bodies
1. understanding of apoptosis, a form of programmed cell death - the animal disposes of a surplus of cells
- importance in the development of cancer
how does studying the fruit fly help science
studying animal genetics
- proof that genes which are units of heredity are carried on chromosomes
- show us how the genetic instructions encoded in DNA direct the development of a fertilized egg cell or zygote into an adult multicellular organism
- understanding genes that are needed to make a properly structured adult body, gut, wings, legs, and eyes - which genes are passed on directly
how has studying the zebrafish helped science
fish can be easily bred and maintained in a lab
they are clear during the first 2 weeks of living, allowing us o observe how cells behave during development
- development of heart and blood vessels
how has studying the mouse helped in science
used as a model organism to help genetics, development, immunology, and cell biology
- it is possible to breed mice with engineered mutations in any gene
- this can be used to test the function of any gene and determine how it works in a living mammals
briefly explain the cell division cycle / cell cycle
the only way to make a new cell is through a pre-existing one, a parent cell must execute an orderly sequence of rxns, duplicate its contents, divide
- any complications can be devastating to the cell
- because proteins are reliant on the cell division process, scientists have worked backwards to see which protein causes abnormalities
T/F yeasts are eukaryotes
true
what as mutations in yeast cells helped us discover
yeast mutants that are defective in their ability to complete cell division have led to the discovery of many genes that control the cell cycle
- Cdc genes
how was Cdc genes found and studied?
paul nurse
S. pombe = a type of yeast
- grows by elongation and fission into 2
- found that Cdc genes called Cdc2 was required to trigger several key events in the cell division cycle
- without being activated by mutation the yeast would not divide
- replacing the faulty Cdc2 gene in S. pombe with a function Cdc2 should repair the defect
explain the relationship between S. cerevisiae and S. pombe yeast
S. cerevisiae divides by forming a small bud that grows steadily until it separates from the mother cell
- wanted to see if the proteins from one type of yeast substitute for those of another
- they took S. cerevisiae DNA into S. pombe cells that contained a temp-sensitive mutation in the Cdc2 gene that kept the cells from dividing when the heat was turned up.
- found that some of the mutant S. pombe cells regained the ability to proliferate at the elevated temp
- rescued cells can divide again and again to form visible colonies of millions of yeast cells
- the rescued cells had a piece of DNA from S. cerevisiae of cdc2
- the result was not that surprising because how different can one yeast be from another - they repeated the experiment with human DNA and the results where the same
T/F the human Cdc2 is not identical to the S. pombe Cdc2
false
Paul Nurse proved this and they are identical because the proteins are almost the same and the AA is almost in the same order
what did the Paul Nurse experiments reveal about proteins in eukaryotes
in very different eukaryotes they have very similar amino acid sequences and can be functionally interchangeable
- also seen that the cell cycle is controlled similarly in every eukaryotic organism alive today
- in the experiment with yeast, the mutant yeasts were rescued and able to divide because of the introduction of a piece of human DNA, this shows that the molecular machinery for reading the information encoded in DNA must be similar from cell to cell and from organism to organism
what does it mean to culture cells in vitro
in glass
the experiments are being tested in a test tube or petri dish
- because they are maintained in a controlled environment, they are accessible to study in ways that are not possible in vivo
what does an in vivo experiment mean
that the experiment is happening inside the organism
T/F when a cell is being grown in a culture it will continue to grow properties that are unique to its origin organism/cell
true
fibroblasts which are connective tissue cells, continue to secrete proteins in vitro
how much water is in cells mass
70%
what is a hydrogen bond
since the bond between H–O is polar and has a slightly negative and positive dipole, when a positive region comes close to a negative region the electrical attraction between them forms a weak bond called a hydrogen bond
- noncovalent and are much weaker than covalent bonds because random thermal motions can easily break them down
- N, O, F
- can produce a network of hydrogen bonds
- without hydrogen bonds, life could not exist
- helps the molecule fold into a particular shape
what does hydrophilic mean
water-loving
- substances that contain polar bonds and can form hydrogen bonds also mix well with water
- DNA, RNA, most proteins, phospholipid bilayer
what does hydrophobic mean
water-fearing molecules
- uncharged with little to no hydrogen bonds
- they do not dissolve in water
what is a noncovalent bond
- quite weak, their energies can sum to create an effective force between 2 molecules
- does not involve the sharing of electrons
- EX: hydrogen bonds, London dispersion
what is an electrostatic attraction
forces that draw together oppositely charged atoms
- ionic bonds and the attractions between other molecules that have polar or covalent bonds
- they are the strongest when the atoms are fully charged like Na+ and Cl-
- when a large molecule with lots of polar functional groups comes close to another molecule with a pattern of positive and negative charges as well, they create weak forces of attraction and bind
what is van der waals attraction
a non-covalent bond when 2 atoms come close to each other, these nonspecific interactions cause an electron cloud which generate a transient attraction between the atoms
- these occur in all type of molecules, even those that are nonpolar and cannot form ionic or hydrogen bonds
rank the bond types from strongest to weakest
covalent
ionic
hydrogen
van der waals
what is a hydrophobic force
- tendency of nonpolar molecules or groups to cluster together in an aqueous (water) environment. These forces arise because water molecules, which are polar, prefer to interact with other polar or charged substances. Since nonpolar molecules cannot form hydrogen bonds with water, they are excluded by water molecules, resulting in the aggregation of nonpolar molecules to minimize their contact with water.
how are hydrophobic forces important
important part in promoting molecular interactions when building cellular membranes - constructed from lipid molecules that have long chains of nonpolar hydrocarbons
since the C-H has no net positive charge, they cannot form hydrogen bonds and are pushed out the network of water molecules inside the cell
what are nucleotides
DNA and RNA are built from subunits called nucleotides that consist of a nitrogen ring that is clicked to a 5carbon sugar + a phosphate group
- the 5carbon sugar is either ribose or deoxyribose
- the nitrogen component is a base (called a base because in acidic conditions they can increase the OH conc)
what are the pyrimidines
CUT
Cytosine, Uracil, Thymine
single ringed - one 6ring
smaller
what are purines
GA
Guanine, Adenine
they are double-ringed - one 6ring fused to a 5ring)
larger
what does ATP stand for
adenosine triphosphate
the transfer energy in metabolic rxns
STRUCTURE
- 3 phosphates linked in series by 2 phosphoanhydride bonds (breaks apart using hydrolysis)
how ATP releases energy
hydrolysis breaks the terminal phosphate group to transfer to another molecule of release energy for biosynthetic reactions
- it releases energy when it is hydrolyzed back to ADP and phosphate
what is the role of nucleotides
the backbone of DNA
- storage and retrieval of biological information
- building blocks for the construction of nucleic acids, long polymers that have nucleotides linked together by phosphodiester bonds
what are nucleic acids
- made from nucleotides with phosphodiester bonds
- 2 different types - ribonucleic acids/RNA and deoxyribonucleic acids/DNA
- RNA = A, C, G, U at the 2’ position of the ribose carbon ring (U is similar to T), single-stranded = 1 polynucleotide chain, serve as more as carriers of molecular instructions
- DNA = A, C, G, T, double-stranded, helix, 2 polynucleotide chains, long-term heredity info
what is a glycosidic bond
the bond that attaches the sugar to the base in nucleotides
placed on a certain carbon - each carbon is numbered and when attached it is called the 5-prime carbon or 5’
What is the difference between the nucleoside and the nucleotide
nucleoside = Base + sugar
nucleotide = Base + sugar + phosphate
what organism was used to start making connections with DNA and heredity
a simple fungi that has genetic information for making proteins
who is the founder of DNA
the structure of DNA was determined by James Watson and Francis Crick
- the structure showed how the DNA is copied and divided
- but Rosaline Franklin examined DNA using x-ray diffraction analysis to see a 3D structure - which was used by Watson and Crick
- found that DNA is a double helical structure that run in opposite directions (anti parallel)
how are the nucleotide subunits within DNA arranged?
the phosphodiester bonds link the 5’ end with the 3’ end of the next nucleotide this is because the ester linkages of the sugar are one either side of the carbon ring which causes the DNA strand to have chemical polarity
what is a base pair
complementary base pairing enables the base pairs to be held with hydrogen bonding and arranged in the interior of the double helix
A - T
C - G
how do organisms differ to each other in terms of DNA
they have different nucleotide sequences which make different complementary bases and codons which code for different proteins
- different genetic code = differences physically/mentally/proteins
what does gene expression mean
the process by which the nucleotide sequence of a gene is transcribed into the nucleotide sequence of an RNA molecule –> translated into an AA sequence for a protein
Gene A –> RNA A –> Protein A
