Bio Test #6 Flashcards
Where do eukaryotic cells occur?
Eukaryotic cells occur in algae, protozoa, fungi, plants, & animals
What are characteristics of Eukaryotic cells?
Euk. cells can be unicellular or multicellular, from 5 micrometers to 100 micrometers
How are eukaryotic cells characterized?
They are characterized by nucleus & organelles
What are the 2 types of Endoplasmic Reticulum?
Smooth ER & Rough ER
What is the structure of smooth ER?
has a network of tubules & vesicles around the nucleus (sometimes continuous with the nucleus); membrane bound organelle
What are functions of Smooth ER?
synthesis of lipids, breaks down carbohydrate, detoxify from drugs, regulates calcium concentration in the cell, produces sex hormones
What is the structure of Rough ER?
has a network of tubules & vesicles (sometimes continuous with nuclear membrane); membrane bound organelle; studded with ribosomes (gibing it a rough appearance)
What are the functions of Rough ER?
synthesis of protein that are needed on the cell membrane of the cell; rough ER surrounds protein with a vesicle
What is the structure of Golgi Apparatus?
series of membrane bound stacks called cisterna(ae)
What are the functions of Golgi Apparatus?
works with ER to repackage & transform proteins or lipids & send them to the right destination; vesicles from ER fuse with cisternae, each region of the Golgi contains enzymes that modify the content of the vesicle
What is the structure of mitochondrian?
double membrane organelle; inner membrane folds & increases its surface and forming crista/ae; fluid inside is called matrix & contains ribosomes and genetic material & enzymes
What is the function of mitochondria?
production of ATP
What is the structure of lysosomes?
membrane bound organelle made by Golgi; it contains digestive enzymes
What is the function of Lysosomes?
digest worn out organelles, food, engulfed bacteria or viruses
What is the structure of ribosomes?
non-membrane bound organelles; made of rRNA & proteins & consist of 2 subunits
What is the function of ribosomes?
protein production (protein that remain in the cell)
What is the structure of centroiles?
barrel shaped organelle made of proteins; part of centrosome
What is the function of centroiles?
involved with the organization of mitotic spindle
What is the structure of Nuclear Envelope?
double membrane; has pores; impermeable to most substance
What is the function of Nuclear Envelope?
protect genetic material; regulate what moves in & out of nucleus
What is the structure of DNA?
deoxyribonucleic acid
What is the structure of Chromosomes?
protein & DNA forms chromatin, arranged into a chromosomes
What are the functions of DNA & Chromosomes?
long term storage of info, controls activity of cell, passes genetic info to daughter cell.
What are characteristics of Mitochondrian?
range in size from 1 to 10 micrometers; different cells have different numbers of mitochondria
What is the structure of cell wall?
Its made of cellulose and has 3 layers
Cellulose
arranged into bundles of fibers called microfibrils
What are the functions of the cell wall?
maintains shape of cell, prevents cell from bursting, allows plant to grow against gravity
What are the 3 layers of the cell wall?
Primary Cell wall (outside)
Middle Lamella
Secondary Cell Wall (inside)
What is the structure of Chloroplast?
double membrane organelle
What is the function of chloroplast?
site of photosynthesis
stroma
liquid inside chloroplast and contains ribosomes, enzymes, & DNA loop
What is the structure of Central Vacuole?
liquid filled vacuole containing water, enzymes, waste, toxic substances
What are the functions of Central Vacuole?
storage of water, support, defense
What are differences of animal cells compared to plants?
no cell wall, has glycogen as carb storage, roundish shape (flexible), no chloroplasts, no vacuoles or temporary vacuoles, has cholesterol in cell membrane, has centrioles
What are differences of plant cells compared to animals?
has cell wall, plants have starch as carb storage, rectangular shape (fixed), have chloroplast always has central vacuoles, do not have cholesterol in cell membrane, has no centrioles
cell membrane
a selectively permeable phospholipid bilayer found in all cells
What is the structure of a phospholipid?
has 3 parts: phospho alcohol head, glycerol, fatty acid tail
Which part of phospholipid is hydrophilic?
the polar phospho alcohol head
Which part of a phospholipid is hydrophobic?
the non-polar fatty acid tails
Why do phospholipids tend to arrange into a bilayer that has continuous & spherical shape?
because of the polar head & non-polar tail
Why is the plasma membrane very flexible & can be broken with enough force?
because the tails are just close to each other but do not form bonds
What allows endo & exocitosis?
the plasma membrane’s flexibility
plasma membrane
semi-permeable membrane & can control what goes in & out of the cell
Why do animal cells have cholesterol interspersed between the phospholipids?
It ensures that the membrane can function at a wider range of temperature
Why do plant cells have a mix of saturated & unsaturated fatty acids?
to allow the membrane to function at different temperatures
What are the types of proteins found in cell membrane?
integral, peripheral, glycoproteins
integral
embedded in the phospholipid membrane, can have many functions (transport, enzyme, hormone binding site, cell adhesion)
Peripheral
adheres temporarily to the cell membrane
can attach to integral protein
glycoproteins
protein & carbohydrate tail
important for cell recognition
What can movements of substances be?
passive and active
Passive
without use of energy (ATP)
Active
needs energy to occur (ATP)
What are types of Passive Transports?
Diffusion and Osmosis
diffusion
the passive movement of particles from an area of high concentration to an area of low concentration
What are types of diffusion?
simple (unaided) and facilitated
Why does diffusion occur?
it results from the random motion of particles
high concentration
an area with lots of molecules
low concentration
an area with few molecules
concentration gradient
difference between high and low
What does it mean when molecules move along the concentration gradient?
that molecules move from an area of high concentration to an area of low concentration
What does it mean when molecules move against the concentration gradient?
to move from low concentration to high concentration
What are factors that affect rate of diffusion?
concentration gradient (greater the concentration difference between 2 areas, the greater diffusion)
distance involved
area involved
barrier to diffusion
distance involved
diffusion over a short distance is faster then diffusion over a long distance
area involved
the larger the area, the greater the diffusion
barrier to diffusion
thinner the membrane the faster the diffusion
What are characteristics of simple diffusion?
through membrane, through channel protein, used for small uncharged molecules (cell membrane) or small & charged (channel protein)
Why isnt energy needed for simple diffusion?
No energy needed because molecule move WITH concentration gradient
What are characteristics of facilitated diffusion?
non channel protein, non channel protein binds to the substance to be moved changes shape & moves substance in, moves larger molecules
Why isn’t energy needed for facilitated diffusion?
does not need energy because substances are moved with the concentration gradient
Why is facilitated very specific?
because each substance will need a different non-channel protein
osmosis
passive movement of water across a semi-permeable membrane, from low solute concentration to high solution concentration
aquaporin
protein water moves through
What are types of active transports?
pumps, exocytosis, endocytosis
How do molecules move in active transports?
molecules move against the concentration gradient (from low concentration to high concentration)
What are characteristics of pumps?
pumps are proteins embedded in the cell membrane, and specific (they can transport only certain molecules) and take the name of whatever they transport
What are the steps of the mechanism of pumps?
- 3 sodium molecules bind to pump in a specific site. Binding of sodium uses ATP phosphorylation
- phosphorylation of ATP releases energy. This energy is used to change the shape of the pump
- Sodium can be released outside the cell & 2 potassium molecules move in to attach to a specific site different from where the sodium had attached
- the binding of potassium to the pump causes the release of the phosphate group. This makes the pump revert to its original shape
- potassium can be released inside the cell. Pump is ready to start again
What are functions of membrane proteins?
Cell recognition, cell adhesion, receptors, enzyme, and transport
In membrane proteins, what’s cell recognition?
Using glycoproteins you identify body’s own cells from foreign cells
In membrane proteins, what’s cell adhesion?
Proteins bind to one another & hold cells together
Connections are called junctions and can be temporary or permanent
In membrane proteins, what’s receptors?
Respond to a chemical messenger & sends a signal inside the cell
In membrane, what’s enzyme?
Breaks down a chemical messenger
Sometimes more enzymes are grouped together to form a metabolic pathway
What’s another name for receptors?
Hormone Binding Sites
In membrane, what’s transport?
it consists of pumps and channels
What’s a membrane protein’s passive & active transport?
pumps are active transports
channels are passive transports
channels
passive transport that allows water & hydrophilic molecules to move through
What are the 2 types of channels?
open & gated
What are the 3 types of gated channels?
ligand, voltage, mechanical
ligand
a chemical messenger opens the gate
voltage
a change in electric potential that opens the gate
mechanical
gate responds to a physical stress (pressure, stretch)
cell cycle
describes the behavior of the cell as it grows and reproduces
What are the 2 phases of the cell cycle?
interphase & cell division
interphase
the longest phase of cell cycle & cells can be found in this phase about 80% of the time
What are the 3 phases of interphase?
G1, S, G2
What are the 2 phases of cell division?
mitosis and cytokinesis
G1 phase
cell has just finished mitosis and the cell is as small as it can be
S phase
synthesis; DNA duplicates (chromosomes make a copy of themselves); cell continues to grow; synthesis of proteins and enzymes involved in DNA duplication
G2 phase
final chance for cell to grow & check up to ensure cell is ready to start dividing
Checkpoint G1
Between G1 & S, proteins check to see if the cell is healthy & the correct size to divide. if it is, the proteins will initiate DNA duplication. If not, the cell will remain in G1 phase
Checkpoint G2
between G2 & Mitosis, DNA repair enzymes check to see if DNA is duplicated correctly. If it is, the protein will send signal to begin mitosis
Mitosis
starts with a deploid cell (2n) & produces 2 identical deploid daughter cells
prophase
nuclear envelope begins to disappear, chromosomes condense (becoming visible), centrioles start migrating to opposite poles, spindle starts forming & attaches to the chromosomes in the centromere
metaphase
chromosomes line up on the equator of the cell (cellplate or metaphase plate), centrioles are at opposite poles
What are the 4 phases of mitosis?
prophase, metaphase, anaphase, telophase
Anaphase
Sister chromatids are pulled apart
Chromosomes move towards opposite poles
Telophase
Chromosomes arrive at opposite poles Chromosomes start to elongate Nuclear membrane reappears Nucleolus reappears Spindle disappears Cell starts elongating for cytokinesis
Cytokinesis
Division of cytoplasm & organelles inside the cell
What’s cytokinesis in animal cells?
Cell membrane starts folding in forming a cleavage furrow. Eventually the 2 sides meet up & the cell separates
What’s cytokines In plant cells?
Golgi releases vesicles that contain cellulose
Vesicles fuse & start forming a cell plate in the middle of a cell
Cell plate grows & separate the cell
What are the functions of mitosis?
Tissue repair
Tissue growth
Asexual reproduction (marine invertebrate
hypertonic
have more solute than the solution it is compared to
isotonic
2 solutions will have the same concentration
hypotonic
solution will have less concentration of a solute than the solution it is compared to
tumor
when cells lose proper control of cell division and start dividing uncontrollably which forms a mass
What are the 2 types of tumors?
benign and malignant
benign
tumor that does not have the potential to spread
malignant
have the potential to spread
metastasize
when a piece can break off and move to other organs through blood system
What are the steps of malignant?
- malignant tumor
2. angiogenesis
angiogenesis
tumor that has recruited blood vessels to get nutrients to keep growing in size, which can form metastasis. If tumor is malignant then patient has cancelled
carcinogens
substances associated with an increased risk of contracting cancer
What gene is associated with cancer?
TP53 when turned off
What are factors that increase the risk of cancer?
radiations, chemicals, tobacco, stress/life, genetics, viruses
What causes a mutation called a thymine dimer?
UV radiators
What forms a kink on the DNA strand?
Two neighboring thymines on the same stand, detach from their partner and form a covalent bond between them
What can repair the kink in a DNA strand?
DNA repair enzymes
What happens to dimers that are not repaired?
It can cause cancer
Why don’t some organisms get skin cancer?
They have DNA repair enzymes called photolyase
Gene therapy
Insert gene to make the enzyme in people at high risk
How are proteins made?
Instructions in DNA: cells make a copy of DNA (mRNA). Then it reads codons, making the protein
mRNA
One stranded with bases of Adenine, Cytosine, Guanine, Uraci
It is always made from matching 3’ to 5’ strand
Codon
A group of 3 bases
What does a codon correspond to?
1 amino acid
What reads codons in mRNA?
Ribosomes
How do ribosomes read codons?
They attach to mRNA and start sliding along until it finds the start codon and keeps sliding along (reading codons) until it finds a stop codon
What are the 3 stop codons?
UAA
UAG
UGA
How do we know what amino acids correspond to certain codons?
Through the genetic code table
What are the characteristics of the genetic code?
Universal and degenerate
Universal
Works in the same way in every organism
Degenerate
More than one codon can call in the amino acid
What starts every protein?
AUG starts every protein with the same amino acid methionine
Gene mutation
A change in the base sequence of an allele
What may gene mutations produce?
It may produce a different allele if the codon codes for a different amino acid
What are different types of mutations?
A mutation can be positive, negative, or neutral
Positive mutation
Causes an advantage
Negative mutation
Causes a disadvantage
Neutral mutation
Causes now effect
What’s the frequency if mutations have advantages to the environment?
The frequency will be higher
What’s the frequency if mutations have disadvantages to the environment?
Frequency will be lower
Mutagens
Substances that cause mutations
How do mutations occur?
Through substitutions, insertions, and deletions
Substitutions
One base is replaced with another
Insertions
One base is added
Deletions
One base is removed
A mRNA strand has 27 codons. How many amino acids in this polypeptide?
26 because you don’t count the stop codon
A gene is 6009 base pairs long. How many amino acids in the polypeptide?
After dividing by three and not counting the stop codon, there are 2002 amino acids
What do the codons UUA, CUA, CUG have in common?
They all have the same amino acid
Karyotype
Number and appearance of chromosomes of a specific organism
How are chromosomes paired?
By size, shape, banding, & position of centromere
When do scientists take pictures of cell for karyotyping?
In metaphase when the chromosomes are most visible
What does each cell contain considering chromosomes?
Each chromosome is made if 2 sister chromatids.
Each cell has to chromosomes for each pair (one father & one mother)
Compare human sex chromosomes
In 23rd position/pair
Female are XX and the same size chromosomes
Male are XY and different size chromosomes
What is karyotype used for?
It is used for pre-natal Diagnosis
Prenatal Diagnosis
Prenatal (before birth)
Diagnosis (to identify something)
Aminocentesis & Chorionic Villus Sampling
Two tests used to obtain cells from fetus. Which take advantage of the fact that the placenta, amnion, & chorion are made by fetus & not mother. There fore the cells of these tissues will have the genotype of the baby
Amniocentesis
Removal of amniotic fluid; done at 14 weeks pregnant; fluid is extracted with syringe inserted into the abdominal wall; liquid extracted contains cells from fetus and is centrifuged, the cells are extracted and cultured. Cultured cells can be karyotyped. The liquid can be tested for neurological disorders (spina bifida)
