Eukaryotes, Prokaryotes & Evolution (2) + (4) Flashcards
outline the difference in ribosomes between EUKs and PROKs
In eukaryotic cells, ribosomes are made of two subunits, composed of almost equal quantities of protein and ribosomal (r)RNA eukaryotic cells 80S prokaryotic cells 70S
what are flagella/cilia
project from the surface of membranes, enclosed by plasma membrane, consisting of microtubules internally
- -moving cells such as sperm, bacteria*
- -move fluid across cell eg. cilia in bronchioles of lungs*
give examples of organisms that source their energy from LIGHT/phototrophic
These organisms get their energy from light and either source their carbon from CO2 (inorganic) or complex carbon compounds.
CARBON DIOXIDE- autotrophic
photoautotrophic, photosynthetic bacteria, some protoctists eg. algae
COMPLEX CARBON COMPOUNDS- heterotrophic
photoheterotrophic eg. purple non-sulfur bacteria (C source is organic matter, not CO2)
what are the 5 functions of the cellulose cell wall
1. mechanical support
cellulose is strong, made of fibrils, microfibrils and cellulose chains (many bonds) strength of cell wall is increased by presence of lignin
2. osmotic support
when water enters the cell, the cell wall resists expansion and internal hydrostatic pressure is created; cell becomes turgid and plant tissue is supported
3. allows easy passage of water through the roots and leaves
4. cell wall can contain:
lignin (wood)
cutin (waxy cuticle)
suberin (roots)
5. orientation of cellulose fibres determines the shape of the plant cell and tf shape of leaves/plant
what is the structure of a mitochondrion
TWO MEMBRANES AND TWO COMPARTMENTS
matrix, inter-membrane space
outer mitochondrial membrane, inner mitochondrial membrane = cristae
DNA and ribosomes in the matrix
what is the far greater degree of variation
interspecific variation
VARIATION BETWEEN INDIVIDUALS OF DIFFERENT SPECIES: far greater than intraspecific variation
Variation INCREASES IN EACH TAXONOMICAL GROUP in the hierarchy of taxa
what is a large central vacuole
- surrounded by the tonoplast (its membrane) and contains sap,*
- which is fluid containing sugars, amino acids, salts*
(may contain waste which is later removed by abscission)
and pigments to attract insects for pollination or animals for seed dispersal anthocyanins
why might shared features not be inherited from a common ancestor (3 marks)
Features may be similar due to convergence/convergent evolution; two organisms become analogous to each other because they have similar environmental pressures on them.
Analogy: similarity of function and superficial resemblance of structures that have different origins
Give the 3 main characteristics of the PROTOCTISTA sub-kingdom protozoa
- All unicellular
- No cell wall
- Heterotrophic
eg. Amoeba, Plasmodium(malarial parasite)
what is an organelle
membrane-bound compartments in a cell with a specific function
State the three types of prokaryotae and briefly describe them
cyanobacteria : photosynthetic, but do not have chloroplasts, contain photosynthetic pigment in the CSM
chemoautotrophic bacteria : nitrobacter, nitrosomonas
heterotrophic bacteria : many are saprotrophic
where does each stage of aerobic respiration occur in a mitochondrion
GLYCOLYSIS cytoplasm
KREBS CYCLE + LINK REACTION mitochondrial matrix
ELECTRON TRANSPORT CHAIN inner mitochondrial membrane (cristae)
where are ribosomes found
either free in the cytoplasm or on RER
what are the 3 functions of intermediate filaments
- anchor the nucleus
- allow cell to cell signalling eg. antigens, WBCs, ECM
- allow cell to cell adhesion in tissues
State the 5 key characteristics of the PROTOCTISTA sub-kingdom: algae
- Cellular structure similar to plants:*
1. contain chloroplasts/chlorophyll
2. cellulose cell wall
3. starch is the storage carbohydrate - No defined organs eg. stem, roots, leaves*
- can be unicellular eg. Chlamydomonas or unicellular eg. seaweed*
give examples of organisms that source their energy through chemical reactions/chemotrophic
- Carbon dioxide/autotrophic; chemoautrophs eg. NITRIFYING bacteria*
- Complex carbon compounds/heterotrophic;*
- chemoheterotrophs; All Animals, all Fungi, many bacteria & protoctists*
what is the difference between GPP + NPP
GPP is before energy is lost in respiration (this is in the plant)
Herbivores + onwards = secondary production
until death, where energy leaves the grazing food chain to the detritivores & decomposers (also leaves this way via egestion/excretion)
state the 5 key characteristics of PROKARYOTAE (bacteria)
unicellular
no nucleus - DNA in cytoplasm
no organelles
Rigid cell wall made of peptidoglycans
Very small cells with 70S ribosomes
why are there eukaryotes and prokaryotes
prokaryotes evolved before eukaryotes. they are unicellular, whereas eukaryotes are unicellular or multicellular. In multicellular organisms, cells differentiate but maintain the same general ultrastructure
what are the 5 key characteristics of the ANIMALIA kingdom
ALL MULTICELLULAR, HETEROTROPHIC
no cell wall
contain a nervous system
glycogen is the storage granule
10 phyla (v diverse), 1 is CHORDATA (vertebrates) containing: mammals, birds, reptiles, amphibians, bony fish + 2 other fish classes. Other phyla are invertebrates.
describe how ANTIBODIES are used to study molecular phylogeny
To see the degree of agglutination between antibodies in antiserum and the blood of different species;
what is an autotroph
(3 marks)
Organisms that manufacture organic substances from inorganic sources, namely:
LIGHT ENERGY in photoautotrophs
ENERGY FROM CHEMICAL REACTIONS in chemoautotrophs
why is the fossil record incomplete
How is cytochrome C oxidase used to give evidence that all life has a common origin? (3 marks)
CYTOCHROME C OXIDASE is a membrane protein involved in aerobic respiration, found in all organisms. (IMM in euk, mesosome/cell m. of prok)
The more closely related a species is, the more similarities in the primary structure/amino acid sequence of cytochrome c protein there are, and the more recent the common ancestor eg. HUMAN & MONKEY : since their common ancestor, number of nucleotide substitutions: 0.2 H and 0.8 M compared to 7.7 H and 6.0 Kangaroo since their common ancestor.
Say yes or no for each of the following characteristics for:
ANIMALIA
- DNA in the cytoplasm
- No organelles
- Unicellular
- Multicellular
- No cell wall
- Cell wall made from…
- Photosynthetic
- Chloroplasts
- Heterotrophic
- Saprotrophic
- Chemoautotrophic
- Nervous system
- Hyphae
- No
- No
- No
- Yes
- Yes
- NO
- No
- No
- Yes
- No
- No
- Yes
- No
give an overview of the evidence for the theory of evolution
Charles Darwin travelled to the Galapagos in 1831-36.
He studied finches on different islands- they had different size + shapes of beaks. These were selected for by the food sources available on each island. ADAPTIVE RADIATION/ DIVERGENT EVOLUTION. from one common ancestor species. Homologies: same structure in different species modified for different uses.
Unfit species are constantly replaced by fitter ones, explaining extinction and unknown animals in the fossil record.
Alfred Wallace studied invertebrates in Papua New Guinea. He found that related species inhabit neighbouring areas. Isolating barriers prevent hybridisation of species and further drive evolution.
what are the differences between eu and pro cells in terms of DNA and organelles
EUKARYOTIC cells contain membrane-bound organelles PROKARYOTIC cells do not contain membrane-bound organelles or a nucleus. EUKARYOTIC cells’ genetic information is contained in the membrane-bound nucleus. EUKARYOTIC cells have linear DNA. PROKARYOTIC cells have a smaller, circular genome, not contained in a nucleus but in the cytoplasm. The nucleoid is where the DNA exists, there is a smaller quantity of DNA.
name the 7 requisite parts and 2 selective parts of a prokaryotic cell
- cytoplasm (contains DNA)
- cell membrane
- mesosome
- cell wall
- capsule
- small ribosomes (compared to eu cells)
- plasmid
- (flagella)
- (pili)
what is ROUGH ENDOPLASMIC RETICULUM
- the site of PROTEIN SYNTHESIS; it is rough due to the ribosomes on its surface*
- it is a network of folded membranes from the outer membrane of the nucleus, forming LAMELLAE/CISTERNAE*
Say yes or no for each of the following characteristics for:
PROKARYOTES
- DNA in the cytoplasm
- No organelles
- Unicellular
- Multicellular
- No cell wall
- Cell wall made from…
- Photosynthetic
- Chloroplasts
- Heterotrophic
- Saprotrophic
- Chemoautotrophic
- Nervous system
- Hyphae
- Yes
- Yes
- Yes
- No
- No
- PEPTIDOGLYCANS
- Yes
- No
- Yes
- Yes
- Yes
- No
- No
what are the two stages of photosynthesis and where do they occur
1st stage: LIGHT DEPENDENT reactions,
occur on the THYLAKOID MEMBRANES
light energy is converted to chemical energy
2nd stage: LIGHT INDEPENDENT reactions, occur in STROMA
carbon dioxide is fixed into organic compounds
which features are found in only in plant cells
- chloroplast
- large central vacuole
- starch granules
- cell wall
what is an extremophile
and a taxon
An organism that can live at extremes of temperature, pH and salinity.
A classificatory group.
what are microfilaments made of, and what are their 3 functions
ACTIN (protein) gives the cell strength, support and keep the cell’s shape allow cell movement eg. changing the shape of the cell; endo/exo-cytosis
Give an example of an overview of evolution by natural selection (5 steps)
A population has some naturally-occurring genetic variation.
A change in the habitat causes a change in the selection acting on the population ; an allele that was of no particular advantage before now becomes advantageous.
Organisms with the allele are more likely to survive, reproduce and so produce offspring ; their offspring have the advantageous allele, so it becomes more frequent in the population.
what is the cellulose cell wall
- It is EXTERIOR to the cell.
- made of CELLULOSE, secreted by the GOLGI APPARATUS of cell.
what is a HETEROTROPH
(3 marks)
An organism that obtains its energy and nutrition from organic matter.
A SAPROTROPH is a type of heterotroph: an organism that obtains its energy and nutrition from dead and decaying matter which has been digested extra-cellularly, by secreting extra-cellular enzymes which break down the matter outside the organism into soluble material which is then absorbed.
give 4 molecular features that are different in archaea to bacteria
Cell wall is not made of peptidoglycan (Bacteria cell wall is)
Histone proteins in combination with DNA (Bacteria DNA not coiled, free-floating in cytoplasm)
Several types of RNA polymerase (bacteria= one type)
Insensitive to streptomycin antibiotic (Bacteria are sensitive)
How is haemoglobin used to show evolutionary links between species
Respiratory pigment present in the animal kingdom.
Species more closely related have more similar primary structure/sequence of amino acids in haemoglobin.
Phylogeny based on this evidence shows that species in the same same genus have a more recent common ancestor that species in the same phylum.
what is a MITOCHONDRION
the site of aerobic respiration
frequent in metabolically active cells eg. liver, muscle, neurones, spermatozoa
describe how PROTEIN SEQUENCING + DNA SEQUENCING are used to study molecular phylogeny + evolutionary relationships
- To see the similarities between sequences of proteins and/or genes found widely in different species eg. cytochrome C (from ETC)*
- and haemoglobin*
what is the chemical formula for aerobic respiration and which stages are involved
C6H12O6 + 6O2 ———-> 6CO2 + 6H2O
- glycolysis*
- Krebs cycle and Link reaction*
- electron transport chain (ox. phos.)*
name the 9 differences between eukaryotic and prokaryotic cells
EU usually larger cells 10-100um diameter PRO usually v small 0.5-10um diameter
EU cell division preceded by mitosis, meiosis PRO cell division preceded by DNA replication
EU nucleus present, nuclear envelope double membrane perforated by pores, DNA in linear chromosomes and combined with histone proteins
EU reproduction; gametes/sex cells with equal contribution from both nuclei
EU cell walls present in plants, fungi, photosynthetic protoctista, do not contain peptidoglycans + mucopeptides
EU many organelles, some bound by double membranes - mitochondria, chloroplast, nucleus
some bound by single membranes
EU protein synthesised in 80S ribosomes
EU some have cilia, flagella, which is larger 200nm diameter PRO some have flagella, pili, which are
what are the four parts of the nucleus and what are their functions
nuclear envelope
DOUBLE MEMBRANE surrounding nucleus
nuclear pores
site of steroid hormone, nucleotide
REGULATES PROTEIN ENTRY, mRNA EXIT
nucleolus
site of TRANSCRIPTION
RIBOSOME FORMATION (rRNA synthesis)
chromatin
2 types: euchromatin and heterochromatin
what is MOLECULAR PHYLOGENY
+ types of MP (3 + 3)
Using different types of molecules to see the extent of the similarities between them in different species, to study their evolutionary relationship/history.
Antibodies, Protein & DNA sequencing, DNA hybridisation
what is the cytoskeleton comprised of and what is its function
It is made of intercellular proteins: microfilaments, intermediate filaments and microtubules.
It provides strength, shape, support and movement within the cell.
what is the cell surface membrane
a boundary between the cell and its environment/extracellular fluid
SELECTIVELY PERMEABLE: only certain material is capable of passing through/permeating it; IT CONTROLS AND REGULATES EVERYTHING THAT ENTERS OR LEAVES THE CELL
- is a functional structure*
- its surface area is increased by microvilli*
- in unicellular organisms eg. amoeba, it allows movement and nutrition*
are protoctista unicellular or multicellular?
what are their two subkingdoms?
Mainly multicellular, but some are also multicellular
2 Subkingdoms: ALGAE
PROTOZOA
there is a third group between the two that have chloroplasts but no cell wall eg. EUGLENA
Explain how natural selection of pesticide resistance in insects has been influenced by humans
- Pesticide bountifully applied by humans to crops
- Most insects die, but a couple have random mutations that lead to an allele conferring resistance to pesticide.
- The survivors have no competition for resources because those without the advantageous allele are killed by the pesticide. Therefore the survivors grow in number more rapidly.
- Additional applications will be less effective + the frequency of resistant insects in the population increases.
name the 8 structures found in animal and plant cells
cytosol/cytoplasm
cell surface membrane
nucleus
endoplasmic reticulum
golgi apparatus
lysosomes
mitochondria
cytoskeleton
Give a description of antibiotic resistance in bacteria influenced by humans
(most prevalent in BACTERIA etc. due to their short life spans)
Mutations are random & already exist in the population. This leads to variation in the susceptibility of bacteria in the population to antibiotics.
Widespread use of antibiotics is the selection pressure for bacteria. The non-resistant bacteria will die. If the course of antibiotics is not finished or the amount of antibiotic is too low, the more resistant individuals will survive.
For the survivors there is very little competition for food etc., therefore they divide quickly and produce a highly resistant population. It can exchange genetic material with other bacteria (horizontal gene transmission). The antibiotic is now ineffective.
describe how DNA HYBRIDISATION can be used to find evolutionary links between different species at a molecular level
- DNA is cut into small sections
- Heating the DNA molecules to break the H-bonds and separate the two strands of the double helix
- Mixing the single-stranded DNA between species to see the extent of hybridisation; the more similar the base sequences are, the better the strands bond and form a double helix, the closer the species are.
wwhat is a species (1 mark)
+ what name is each one given
A group of organisms that can interbreed to produce fertile offspring.
Binomial nomenclature: scientific name of 2 parts eg.
Homo sapiens
why did the domain classification system arise (2 marks) and what are the domains (1 )
The original classification of taxonomical groups KPCOFGS used anatomical and physiological (visible) similarities and differences.
In the late 20th century, the domains were introduced to give greater significance to similarities and differences in molecular biology, i.e. cellular and biochemical.
3 domains: EUKARYOTAE all kingdoms except prokaryotae
ARCHAEBACTERIA extremophile bacteria
EUBACTERIA all other bacteria
what is the lesser degree of variation
INTRAspecific variation
variation between individuals of the same species
the greater the genetic diversity of a species, the greater the intraspecific variation.
Genetic diversity in species is due to meiosis and sexual reproduction ( and random mutation leading to new alleles).
State the other 4 requirements of an ancestral species in order to evolve by natural selection (not time or population characteristics)
- Needs an environmental condition which causes a pressure ( called a selection pressure/natural selection eg. disease)
- Needs the offspring to look like them i.e. because the alleles are inherited)
- These offspring must survive and reproduce
- There must be an increase in the proportion of the population possessing the advantageous characteristic (+ decrease in the proportion of the population that has the disadvantageous allele)
How can we use BIOCHEMISTRY to provide evidence for all life having a common origin:
- Only 20 amino acids are used to make proteins- the same 20 in all organisms. Genetic code specifying amino acids is the same in all organisms and universal.
- Molecule of inheritance in all cellular organisms - eu and pro- is DNA.
- ATP is the universal currency for energy in the cells of all organisms.
Analysis of AAs of proteins from closely related species are very similar eg. cytochrome C, haemoglobin.
define phylogeny (1 mark)
Making evolutionary links eg. physiological or anatomical similarities.
Similarities are shared features that are inherited from a common ancestor.
These lead to the natural classification system, which is based on similarities.
what is classification
Placing living organisms into groups (taxons) according to similarities + differences.
(each successive group contains more and more different kinds of organisms- (D)KPCOFGS)
what are <em>plasmodesmata</em>
small gaps in cell wall and the middle lamellae (made of pectin, point of contact between 2 cell walls) where the cytoplasm of adjacent cells meet
what is a chloroplast
- site of photosynthesis*
- found in the palisade mesophyll layer of the leaf*
what is a lysosome
a vesicle containing hydrolytic enzymes lysozymes which degrade waste/unwanted substances in the cell
created by the golgi apparatus
classify the human race into its taxons, from most inclusive to least inclusive
- (Domain: Eukaryotae)*
- Kingdom:* Animalia
- Phylum:* Chordata
- Class:* Mammalia
- Order:* Primates
- Family:* Hominidae
- Genus:* Homo
- Species:* sapiens
what is the pathway of gaseous nitrogen fixation by prokaryotes
N2 → NH3 → amino acids → protein → cytoplasm/membranes/enzymes
N2 is fixed by the nitrogenase enzyme, energy from ATP + reducing power of H+ from resp. of glucose from host plant
NITROGENASE is inactivated by oxygen
Ammonia is combined with keto acids to form amino acids
what is the structure of a chloroplast
thylakoid membranes, arranged into grana (granum, a stack of t. m.), connected by integranal lamellae, surrounded by stroma
DNA, ribosomes, starch granules
all surrounded by chloroplast envelope
what is the CAPSULE
MESOSOME
CELL WALL
PLASMID
capsule; slimy layer surrounding cell wall
IT ALLOWS CELL-CELL ADHESION + COLONY FORMATION
mesosome; invaginations of the plasma membrane, INCREASED SURFACE AREA FOR REACTIONS eg. electron transport chain, site of enzymes and pigments
cell wall; made of peptidoglycans and mucopeptides to avoid osmotic swell
plasmid DNA; confers antibiotic resistance
State the first 4 requirements of the evolution of a new species by natural selection (time + within population)
THE ANCESTRAL SPECIES NEEDS:
- Geological time- evidence provided by fossils, supported by DNA and molecular evidence
- Variation in the species-
occurs by random mutations, most are detrimental but a few are advantageous- these give the individual a better chance of survival. TYPES: continous + discontinuous. CAUSES of VARIATION: genetic + environmental
- Large numbers in the population/overproduction and competition for resources
- Some individuals must be better adapted because of their mutation; these individuals must survive and REPRODUCE
what is cytoplasm
cytosol + all organelles (except nucleus)
site of many chemical/metabolic reactions
surrounded by the cell surface m/plasma m
what are fossils + why are they used as evidence for evolution
Mineralised or other preserved remains of once living organisms.
Fossils are formed from faeces, footprints, burrows etc.
Layers of sedimentary rock can reveal the age of fossils i.e. the age of the rock. (Radiocarbon dating can be used on remains of 50,000 years ago or less).
Fossils can be used to show where there are links between extinct + extant organisms eg. archaeopleryx, the link between birds and reptiles.
what is GOLGI APPARATUS
the site of post-translational protein and lipid modification (from RER and SER, respectively). they are transported in vesicles to intra or extracellular destinations
some vesicles remain in the cell eg. lysosomes, peroxisomes. others exocytose eg. digestive enzymes, hormones
appearance- many vesicles at ends of lamellae, more curved than SER
list 5 defining characteristics of the kingdom PLANTAE
+ give an example of a phyla
- all multicellular
- photosynthetic
- contain chloroplasts/chlorophyll
- contain cellulose cell wall
- starch is the storage carboydrate
Examples of PHYLA: Liverworts + mosses, Ferns, Conifers, Angiosperms
what are centrioles
CENTRIOLES for mitosis and cell division
make up the centrosomes (only in animal cell division) which duplicate and move to opposite poles of the cell before division
what is a prokaryotic cell
an UNICELLULAR organism; ancestor of all living organisms (the origins of mitochondria + chloroplasts)
NO NUCLEUS, NO MEMBRANE-BOUND ORGANELLES
the DNA is contained in CYTOPLASM
Say yes or no for each of the following characteristics for:
FUNGI
- DNA in the cytoplasm
- No organelles
- Unicellular
- Multicellular
- No cell wall
- Cell wall made from…
- Photosynthetic
- Chloroplasts
- Heterotrophic
- Saprotrophic
- Chemoautotrophic
- Nervous system
- Hyphae
- No
- No
- Yes
- Yes
- No
- CHITIN
- No
- No
- Yes
- Yes
- No
- No
- Yes
which modifications are made in the golgi apparatus
- the organelle in which post-translational modifications are made to proteins*
1. ADDITION TO PROTEINS
the addition of a carbohydrate chain to the protein, creating glycoproteins, or the addition of lipids to the protein, creating glycolipids
- ADDITION OF PROSTHETIC GROUPS
to proteins, such as haem (blood)
what are the advantages of binomial nomenclature (4)
- to overcome different common names being used in different countries
- to overcome names in different parts of a country
- translation of languages or dialects may vary
- the same common name may be used for different species
state the traditional five-kingdom system and the more contemporary six-kingdom system
MONERA - PROTISTA - PLANTAE - FUNGI - ANIMALIA
Bacteria, Archaea, Protista, Plantae, Fungi, Animalia
what is a ribosome
large structure, approx. 20nm, seen by an electron microscope, not LM
made of PROTEINS and RIBOSOMAL RNA (rRNA)
80S in eukaryotic cells, 2 subunits
70S in prokaryotic cells, mitochondria of eus, chloroplast of eus
not surrounded by a membrane
what is the chemical formula for photosynthesis
6H2O + 6CO2 ———> 2(C3H6O3) + 6O2
which features/organelles are found only in animal cells
- centrioles
- flagella/cilia
Say yes or no for each of the following characteristics for:
PLANTAE
- DNA in the cytoplasm
- No organelles
- Unicellular
- Multicellular
- No cell wall
- Cell wall made from…
- Photosynthetic
- Chloroplasts
- Heterotrophic
- Saprotrophic
- Chemoautotrophic
- Nervous system
- Hyphae
- No
- No
- No
- Yes
- No
- CELLULOSE
- Yes
- Yes
- No
- No
- No
- No
- No
what is SMOOTH ENDOPLASMIC RETICULUM
the site of lipid synthesis and carbohydrate synthesis
no ribosomes. - smooth appearance
Say yes or no for each of the following characteristics for:
PROTOCTISTA
- DNA in the cytoplasm
- No organelles
- Unicellular
- Multicellular
- No cell wall
- Cell wall made from…
- Photosynthetic
- Chloroplasts
- Heterotrophic
- Saprotrophic
- Chemoautotrophic
- Nervous system
- Hyphae
1.
- No
- No
- Yes
- Yes
- No
- CELLULOSE
- Yes
- Yes
- Yes
- No
- No
- No
- No
what are the 6 key characteristics of the kingdom fungi
They contain a cell wall made of chitin
Not photosynthetic
Heterotrophic, and mostly saprotrophic
Glycogen is the main storage carbohydrate
Mainly multicellular but may be unicellular eg. yeast
Contain thread-like projections ; hyphae. They criss-cross into their food source to form mycelium.
what is divergent evolution and what are homologous features
(1 mark each)
what are the 3 functions of microtubules
- allow movement of organelles within the cells
- form the spindle in mitosis, allowing movement of chromosomes to opposite poles of the dividing cell
- make up cilia, flagella, centrioles, undulipodia
