intro to cell structure and function Flashcards
all living organisms are made of what?
cells
what are the simplest forms of living things?
unicellular
how to unicellular organisms multiply?
by dividing into two
cells are essentially small bags made of what?
bound by membrane containing a liquid made of water and a variety of chemicals, proteins, lipids, and carbohydrates
how have cells evolved over thousands of years?
natural selection- random genetic variation that’s passed on from one generation to the next and by selection of cells that can survive the environment in which they live
how is it believed life started on earth?
multiplication of a polynucleotide molecule in a rich “soup” of nucleotides which began to propagate and develop of 3D structure by bonding with nucleotides and other molecules and became more stable and able to carry information from one generation to the next while also having a specific function associated with their sequence and structure
what are the three key steps for the formation of cells?
- generation of self-replicating RNA
- production of proteins
- formation of the cell membrane
what is the original repositories of genetic information?
RNA moelcules
what became the keeper of the genetic code throughout the process of evolution?
DNA
what is the simplest cell form among today’s cells?
mycoplasma
what are mycoplasma?
small bacterium-like organisms that lead a parasitic life
how do mycoplasma synthesize 750 proteins essential for their survival?
structural proteins and enzymes synthesize small molecules inside the cell that are not available in the environment, which are capable of maintaining a suitable chemical environment within the cell by redistributing energy and organizing biochemical reactions in an optimal fashion.
what are the simplest organisms found in most environments and represent what?
bacteria
prokaryotes
what are the shapes of bacteria?
cocci and bacilli
how does bacteria differ from mycoplasma?
bacteria is larger and has a thick protective cell wall
what is the function of the cell membrane?
encloses nucleic acids, DNA, RNA, proteins, etc.
what is special about archaebacteria?
live in a variety of harsh environments such as ocean depths, salt brines, and hot acid springs. Some are even capable of converting carbon dioxide to methane
what is special about cyanobacteria?
obtain their nitrogen directly from atmospheric N2
how did anaerobic bacteria survive when the atmosphere became oxygen dense?
identifying niches that were low in oxygen or devoid of oxygen to support their existence
what is the most abundant cell type on earth?
bacteria
what organelles do eukaryotes have that prokaryotes don’t?
Nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus etc.
what are the two types of eukaryotic cells?
animal and plant
what is the difference between plant and animal cells?
animal: have a cell membrane and centrioles that play a vital role in cell division
plant: surrounded by cell walls with an underlying plasma membrane and they also have large vacuoles and specialized structures called chloroplasts that are essential for photosynthesis.
what are organisms of prokaryotes
bacteria and cyanobacteria
what are organisms of eukaryotes
Protists, fungi, plants and animals.
compare the metabolism of prokaryotes and eukaryotes
pro: anaerobic or aerobic
eu: aerobic
how do prokaryotes DNA differ from eukaryotes
pro: Circular DNA In cytoplasm
eu: Long stretches of DNA containing coding and non-coding regions, organized as chromatin and located in the nucleus
how do RNA and protein differ with prokaryotes and eukaryotes
pro: RNA and protein in the same compartment
eu: RNA synthesized in the nucleus, proteins in the cytoplasm
in eukaryotes, what is the cytoskeleton composed of? how is it different from prokaryotes?
protein filaments, cytoplasmic streaming, capable of endocytosis and exocytosis
pro: No cytoskeleton. No cytoplasmic streaming, endocytosis or exocytosis
how do prokaryotes divide vs eukaryotes?
pro: binary fission
eu: mitosis or meiosis
how is the nucleus separated from cytoplasm>
nuclear envelope made of two membranes
what is chromatin?
chromosomal DNA within the nucleus in a tightly wound form that uses histone proteins
what is the nucleolus?
dense body which is the site of RNA assembly
what are nuclear pores?
openings in the nuclear envelope that allow for exchange of contents between the cytosol and nucleus
what is the nucleus?
regulates gene expression, coordinates protein synthesis and determines how a cell responds to a stimulus.
what is the endoplasmic reticulum (ER)?
series of membranous tubes or sacs that lies adjacent to the nucleus.
membrane is continuous with the outer membrane of the nuclear envelope.
why is the rough ER called “rough” and what does it do?
has ribosomes attached to its surface which are involved in active protein synthesis
lumen serves as the receiving site for the secretion of assembled peptide chains.
what is the smooth ER?
tubular and does not have ribosomes on its surface
plays a role in lipid metabolism.
what is the golgi apparatus?
system of stacked flattened sacs that help to modify, sort and package proteins and macromolecules and also prepare them for shipment to various parts of the cell for further processing or secretion via small vesicles
what are lysosomes?
membrane bound vesicles that contain hydrolytic enzymes that are responsible for intracellular digestion
what are peroxisomes?
membrane-bound vesicles but they contain oxidative enzymes that generate hydrogen peroxide and scavenge oxidative radicals.
what is mitochondria?
sites of power generation for all eukaryotic cells.
how does mitochondria generate ATP?
by using oxygen and nutrient molecules
They contain a large number of enzymes that participate in redox reactions involved in the electron transport chain. This generates protons that drive the formation of ATP that is used as an energy source by the cell.
what is cytosol
liquid that contains various chemicals and macromolecules where the organelles are suspended
also contains filaments that give the cell its shape and helps with movement and cell division.
what are the three main kinds of cytosol filament?
microtubules
intermediate filaments
actin filaments
what is the simplest of eukaryotic cells?
unicellular protists
what is special about the unicellular protists?
utilize photosynthesis or be carnivorous, and can be motile or non-motile. They can also possess muscle-like contractile bundles, flagella for movement, mouth parts, or pseudopods
describe the protozoan, Didinium
It can swim around in water using cilia that use microtubules for movement, and it uses stinging darts for paralyzing and devouring its prey
when did multicellular organisms occur?
when cells closely related by ancestry differentiated from each other and developed a specific feature to a high degree., leading to the different parts of a multicellular organism
how many different types of cells are in the human body?
200
describe epithelia
- formed by cells stacked on top of a basement membrane
- line the inner and outer surfaces of the body
- play a role in protection, absorption, secretion and trapping foreign substances
- form aggregations called glands that have specialized secretions
describe connective tissue
- acts as the “glue” between various organs and tissues
- made up of an extracellular matrix, fibers and cells including fibroblasts that produce the fibers and extracellular matrix
describe blood
- mixture of water, proteins and specialized cells.
- Erythrocytes make up a large fraction of blood cells which contain hemoglobin that helps to carry oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs
- White blood cells are part of the immune system and they help to protect the organism from invading microbes.
describe muscle cells and the three main types
produce mechanical force by their contraction
1. skeletal muscle- attached to skeletal structures
2. cardiac muscle- makes up the heart
3. smooth muscle- makes up the internal organs
describe nervous tissue
composed of neurons or nerve cells that are specialized for communication
how do neurons communicate with each other?
synapses
what are neurotransmitters?
electrical impulses and specialized chemicals to transmit information used by neurons
what do neurons makeup and what is their purpose?
brain, spinal cord, and peripheral nerves
they coordinate all body functions including secretions and movement
how does the nervous system use sensory nerves and sensory cells?
to obtain information from the outside environment and responds accordingly
what are the 6 elements cells are cmposed of?
- carbon
- hydrogen
- oxygen
- nitrogen
- phosphorus
- sulfur
what percentage of the cell does water take up?
70%
what compound is the majority of the cell made of and why?
carbon because it has the unique capacity to form large, complex molecules
what are the building blocks of the cell?
carbohydrates
proteins
lipids
what are the cells 4 families of small organic molecules?
- sugars
- fatty acids
- amino acids
- nucleotides
describe amino acids
- building blocks of proteins
- have an amino group and carboxyl group and they ionize at ph of 7
list the acidic side chains of amino acids
aspartic acid, glutamic acid.
list the basic side chains of amino acids
Lysine, arginine and histidine.
list the uncharged polar side chains of amino acids
Asparagine, glutamine, cysteine, serine, threonine, tyrosine
list the non-polar side chains of amino acids
Alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan, glycine
how many amino acids joined make up a peptide
30-100
what makes up a nucleotide?
5-carbon sugar, a phosphate and a base
what makes up a nucleoside?
Base + sugar
what are the two types of bases for a nucleotide?
purines (eg. Adenine and Guanine) and pyrimidines (eg. Cytosine, Uracil, Thymine)
what are the two types of sugar for a nucleotide?
Ribose and 2-deoxyribose.
Nucleotides are strung together by __________ bonds to form nucleic acids
phosphodiester
give examples of nucleotide functions besides forming nucleic acids
- carry chemical energy in their easily hydrolyzed acid anhydride bonds. Ex. adenosine triphosphate (ATP)
- join with other molecules to form coenzymes. Ex. Coenzyme A
- used as intracellular signaling molecules. Ex. adenosine monophosphate (AMP)
how do animals obtain their energy?
by consuming organic molecules in plants and oxidizing them in a series of enzyme-catalyzed chemical reactions that generate ATP
why do cells continuously use ATP?
to drive internal processes of macromolecular synthesis and breakdown
define catabolism
breakdown of larger molecules occurs due to the action of specific enzymes or a process
explain how food is broken down to generate ATP
- digestion: protein broken down into amino acids, fats into fatty acids, and polysaccharides into sugars
- smaller molecules enter cells and further degraded in the cytosol
- carbon and hydrogen atoms of sugars converted into pyruvate via glycolysis which enters the mitochondria where its converted to the acetyl groups of acetyl CoA
- acetyl CoA gives rise to a large amount of energy
- Oxidation of fatty acids can also give rise to acetyl CoA
- ATP is generated when the acetyl group of acetyl CoA is completely degraded to carbon dioxide and water
what makes anaerobic generation of ATP via glycolysis efficient?
Adding an oxygen-requiring step makes it highly efficient for extracting energy from food molecules beginning with the Kreb Cycle and ending with oxidative phosphorylation
what happens during oxidative phosphorylation?
NADH and FADH2 transfer the electrons that they have accumulated to molecular Oxygen and release a large amount of ATP
where do reactions like oxidative phosphorylation, kreb cycle, and glycolysis happen?
mitochondria
where is the energy for biosynthesis of cellular proteins, lipids, and other macromolecules derived from?
hydrolysis of ATP
how are Large proteins and nucleic acids assembled from small activated precursor molecules?
by repetitive dehydration reactions.
