Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
66 Cards in this Set
- Front
- Back
how many electrons can orbitals hold?
|
who gives a fuck?
just kidding. 2. |
|
Shell Model
|
First shell
Lowest energy Holds 1 orbital with up to 2 electrons Second shell 4 orbitals hold up to 8 electrons |
|
Ionic Bonds
|
One atom loses electrons to become a positively charged ion
Another atom gains these electrons to become a negatively charged ion The charge difference attracts the two ions to each other & keeps them together |
|
Covalent Bonds
|
Atoms share a pair or pairs of electrons to fill the outermost shell
|
|
Nonpolar covalent bond
|
Atoms share electrons equally
Example: Hydrogen gas (H-H) |
|
Polar covalent bond
|
Electrons spend more time near nucleus with most protons
Example: Water - electrons more attracted to O nucleus than to H nuclei |
|
Hydrogen Bonds
|
Molecule held together by polar covalent bonds has no net charge
However, atoms of the molecule carry different charges Atom in one polar covalent molecule can be attracted to oppositely charged atom in another such molecule |
|
Free Radicals
|
molecules that lack a full complement of electrons in their outer shells
High capacity to oxidize Can readily “steal” an electron from another, stable molecule |
|
Antioxidant
|
chemicals that can give up an electron to a free radical before it damages cell
Some manufactured by the body (melatonin) Others available in diet (vitamin C, vitamin E, carotenoids |
|
Condensation reactions
|
form polymers from subunits; Enzymes remove -OH from one molecule, H from another; form bond between two molecules; discarded atoms can join to form water
|
|
Hydrolysis rxns
|
break polymers into smaller units; enzymes split molecules into two or more parts; an -OH group and an H atom derived from water are attached at exposed sites
|
|
Carbohydrates (sugars)
|
come in different forms (classes):
Monosaccharides (simple sugars) Oligosaccharides (short-chain carbohydrates) Polysaccharides (complex carbohydrates) Most sugars are composed of carbon, hydrogen and oxygen atoms in a 1:2:1 ratio Most abundant biological molecule |
|
Lipids
|
Most include fatty acids: Fats; Phospholipids; Waxes
Sterols and their derivatives have no fatty acids Tend to be insoluble in water |
|
Proteins
|
A protein is a chain of amino acids linked by peptide bonds
Peptide bonds are covalent bonds that link amino groups of one amino acid with carboxyl groups of the next via condensation reactions |
|
Protein Structure
|
Primary structure = sequence of amino acids; unique
Secondary structure = local regions of hydrogen bond formation between different parts of the peptide chain: helix or pleated sheet Tertiary structure = final folding of secondary structures into a functional unit Quaternary structure = multiple tertiary structures held together |
|
cell theory
|
Every organism is composed of one or more cells
The cell is the smallest unit having properties of life All cells come from pre-existing cells |
|
3 common features of cells
|
A plasma membrane
An internal region where DNA is stored Cytoplasm |
|
advantages of small cells
|
Surface-to-volume ratio is important: the bigger a cell is, the less surface area there is per unit volume
Above a certain size, material cannot be moved in or out of cell fast enough; in this case the cell dies |
|
plasma membrane (lipid bilayer)
|
the mediator of exchange
Gives membrane its fluid properties and determines function Two layers of phospholipids: hydrophilic heads face outward and hydrophobic tails face the center Structure: extremely thin; mosaic of proteins and lipids Lipids give membrane its fluid quality Proteins carry out most membrane functions Transports, Receptors, Recognition proteins, Adhesion proteins |
|
Nucleus
|
Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm
Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells Components: nuclear envelope, nucleoplasm, nucleolus Chromatin: cell’s collection of DNA + associated proteins A chromosome is one DNA molecule and its associated proteins; the appearance of chromosomes change as the cell divides |
|
The Endomembrane System
|
Group of related organelles; assembles lipids; modifies new polypeptides; sorts and ships products to various destinations
Rough ER = sacs studded with ribosomes; protein modification Smooth ER = interconnected tubules w/o ribosomes; lipid assembly; toxin inactivation Golgi = finishes modifications to proteins + lipids; packages for transport within cell or to surface (vesicle trafficking) |
|
Mitochondria
|
ATP-producing powerhouses
Carry out the most efficient energy-releasing reactions Reactions require oxygen Structure: two compartments Outer membrane faces cytoplasm Inner membrane folds back on itself ATP-making machinery is embedded in the inner mitochondrial membrane |
|
Cytoskeleton
|
Basis for cell shape and internal organization
Enables organelle movement within cells and, in some cases, cell motility Main elements are microtubules (spatial organization), microfilaments (cell rearrangements), and intermediate filaments (strong anchors) |
|
Selective Permeability
|
PM controls movement
Diffusion: net movement of like molecules or ions down a concentration gradient Osmosis = diffusion of water Tonicity Diffusion + Osmosis = no energy |
|
Transport Proteins + Transport
|
Transport proteins span the lipid bilayer
Interior is able to open to both sides Change shape when they interact with solute Play roles in passive and active transport Passive transport = flow of solutes through the interior of passive transport proteins down their concentration gradients; no energy needed Active transport = net diffusion of solute is against concentration gradient; transport protein must be activated ATP gives up phosphate to activate protein Binding of ATP changes protein shape and affinity for solute Exocytosis and endocytosis also occur (PM vesicles) |
|
Enzyme Structure + Function
|
Enzymes speed the rate at which certain reactions occur
An enzyme recognizes and binds to only certain substrates (Induced-Fit Model) Reactions do not alter or use up enzyme molecules Enzyme-substrate complexes are short lived and reversible Factors influencing activity Temperature, pH, salt concentration, coenzymes + cofactors Toxins will also affect |
|
Aerobic Respiration
|
Aerobic respiration converts glucose to CO2 + H2O, in the process allowing for the production of ATP
Glycolysis: glucose to 2 pyruvate in cytoplasm Glycolysis has 2 overall steps: one uses energy to prime the system, the other produces energy (yield: 2ATP + 2NADH) NADH = electron carrier Pyruvate enters mitochondria Krebs Cycle Preparatory reactions occur prior to entrance to Krebs Products: Coenzyme A; 2 CO2; 3 NADH; FADH2; ATP NADH, FADH2 need to be oxidized (reset) and their electrons converted to ATP Electron Transport Chain (ETC) ETC passes electrons to the final electron acceptor: oxygen As electrons move, H+ is moved from inner to outer compartment; flow back across membrane drives ATP synthesis |
|
Glucose Utilization
|
When glucose is present, it is absorbed into the blood
Pancreas releases insulin that stimulates glucose uptake by cells Cells convert glucose to glucose-6-phosphate, trapping glucose in the cytoplasm where it can be used for glycolysis If glucose intake is higher than what is needed, glucose-6-phosphate is diverted into glycogen synthesis for storage (in liver and muscle) When glucose levels in the blood drop, the pancreas releases glucagon which stimulates liver cells to convert glycogen back to glucose and to release it to the blood (muscle cells do not release their stored glycogen) Glycogen makes up only about 1% of the body’s energy reserves; proteins make up 21% of energy reserves; fats make up the bulk of reserves (78%) |
|
Energy from Fats + Proteins
|
Most stored fats are triglycerides
Triglycerides are broken down to glycerol and fatty acids Glycerol is converted to PGAL, an intermediate of glycolysis Fatty acids are broken down and converted to acetyl-CoA, which enters Krebs cycle Proteins are broken down to amino acids Amino acids are broken apart Amino group is removed; ammonia forms, is converted to urea, and is excreted Carbon backbones can enter the Krebs cycle or its preparatory reactions |
|
Reproduction + Cell Division
|
Parents produce a new generation of cells or multi-celled individuals like themselves
Parents must provide daughter cells with hereditary instructions, encoded in DNA, and enough metabolic machinery to start up their own operation Mitosis, division of cytoplasm Body growth and tissue repair Meiosis, division of cytoplasm Formation of gametes, sexual reproduction |
|
Chromosomes
|
Chromosomes are DNA molecules & attached proteins
Chromosome Number = the sum total of chromosomes within a given cell type Somatic cells Chromosome number is diploid (2n; 46 for humans) Two of each type of chromosome (2 sets of 23; one set from father, one set from mother) Gametes Chromosome number is haploid (n; 23 for humans) One of each chromosome type Chromosomes are duplicated in preparation for mitosis |
|
Cell Cycle
|
Cycle starts when a new cell forms
During cycle, cell increases in mass and duplicates its chromosomes Cycle ends when the new cell divides Interphase is the longest phase and includes G1, S, G2 Mitosis involves division and encompasses 4 stages followed by physical division |
|
Sexual Reproduction
|
Chromosomes are duplicated in germ cells
Germ cells undergo meiosis and cytoplasmic division Cellular descendants of germ cells become gametes Gametes meet at fertilization Meiosis involves 2 consecutive divisions to reduce the number of chromosomes |
|
Random Alignment
|
During transition between prophase I and metaphase I, microtubules from spindle poles attach to kinetochores of chromosomes
Initial contacts between microtubules and chromosomes are random Either the maternal or paternal member of a homologous pair can end up at either pole The chromosomes in a gamete are a mix of chromosomes from the two parents |
|
Fertilization
|
Male and female gametes unite and nuclei fuse
Fusion of two haploid nuclei produces diploid nucleus in the zygote Which two gametes unite is random Adds to variation among offspring |
|
Mitosis
|
Mitosis
Functions Asexual reproduction Growth, repair Occurs in somatic cells Two diploid cells are produced, each identical to the parent (produces clones) |
|
Meiosis
|
Function
Sexual reproduction Occurs in germ cells Produces variable offspring Four haploid cells are produced, each different from the parent and from one another |
|
Alleles
|
different forms of the same gene
Dominant allele masks a recessive allele that is paired with it Homozygous = two identical alleles (AA or aa) at same locus Heterozygous = two different alleles (Aa) at same locus Alleles form the genotype (unseen); phenotype = the expression of the genotype (observed) |
|
Genes
|
basic units of information about specific traits (genes are DNA)
|
|
Principle of Gene Segregation
|
An individual inherits a unit of information (allele) about a trait from each parent
During gamete formation, the alleles segregate from each other Homozygous parents produce gametes of same type alleles Heterozygous parents would produce 2 games of each allele type Predictable patterns of segregation |
|
Genetic Probabilities
|
the chance that each outcome of a given event will occur is proportional to the number of ways that event can be reached
For heterozygous parents, 4 events are possible “C” = dominant “c” = recessive 3/4 chance of dominant Probabilities are the same for each child |
|
Dihybrid Cross
|
Complexity rises when look at multiple loci
Parents CCDD x ccdd will produce F1 generation that is all CcDd Parents CcDd x CcDd produce 4 outcomes in the F2 generation Again, genes assort independently |
|
Pleiotropy
|
Alleles at a single locus may have effects on two or more traits
Classic example is the effects of the mutant allele at the beta-globin locus that gives rise to sickle-cell anemia Two alleles: HbA (encodes normal beta-hemoglobin chain) and HbS (mutant allele encodes defective chain) HbS homozygotes produce only the defective hemoglobin; suffer from sickle-cell anemia |
|
Sickle cell anemia:
|
At low oxygen levels, cells with only HbS hemoglobin “sickle” and stick together
This impedes oxygen delivery and blood flow Over time, it causes damage throughout the body |
|
Homologous Chromosomes
|
Homologous autosomes are identical in length, size, shape, and gene sequence
Sex chromosomes are non-identical but are still considered homologous Homologous chromosomes interact, then segregate from one another during meiosis Alleles on homologous chromosomes may be same or different |
|
Sex Determination
|
Human X and Y chromosomes function as homologues during meiosis
The X chromosome carries more than 2,300 genes, most genes deal with nonsexual traits Genes on X chromosome can be expressed in both males and females The Y chromosome has fewer than two dozen genes identified, one of which is the master gene for male sex determination SRY gene (sex-determining region of Y) SRY present, testes form SRY absent, ovaries form |
|
X Chromosome Inactivation
|
Mammalian females have two X chromosomes per cell
One X is inactivated per cell – produces a Barr Body Condensed X chromosome that is visible but so tightly packed it cannot be expressed Inactivation is random – it can be either the maternal or paternal X chromosome |
|
Gene Linkage
|
Genes on the same chromosome are “linked”
Crossing over can rearrange linked genes Farther apart two genes are on chromosome, the more they are to be rearranged by crossing over |
|
Human Genetic Analysis
|
Pedigrees allow for the tracking of genes through families
Knowledge of probability and Mendelian patterns used to suggest basis of a trait Can be used to track genetic abnormalities (rare, uncommon versions of traits) or genetic disorders (inherited conditions causing mild to severe diseases) Abnormality: polydactyly (extra fingers and/or toes) Disorder: Huntington disease Why do genetic disorders continue if harmful? Mutation introduces new rare alleles In heterozygotes, harmful allele is masked, so it can still be passed on to offspring |
|
Autosomal-Recessive Inheritance
|
If parents are both heterozygous, child will have a 25% chance of being affected, and a 50% chance of being a carrier
Examples: Cystic fibrosis Phenylketonuria (PKU) Tay-Sachs disease |
|
Autosomal-Dominant Inheritance
|
Trait typically appears in every generation (carriers in this case show disease)
Examples: Huntington disorder Achondroplasia Familial hyper-cholesterolemia |
|
X-Linked Recessive Inheritance
|
Males show disorder more than females
Son cannot inherit disorder from his father X-linked recessive Red/green color blindness Hemophilia A Duchenne muscular dystrophy (DMD) X-linked dominant Faulty enamel trait |
|
Changes to Chromosome Structure
Deletions: |
permanent loss of part of a chromosome and its genes; may occur sponataneously, or be due to a virus, irradiation, or other environmental factors. Most are lethal or cause serious disease
|
|
Changes to Chromosome Structure
|
permanent loss of part of a chromosome and its genes; may occur sponataneously, or be due to a virus, irradiation, or other environmental factors. Most are lethal or cause serious disease
|
|
Changes to Chromosome Structure
Duplications |
gene sequence is repeated several to hundreds of times; occur in normal chromosomes and may have an adaptive advantage
|
|
Translocation:
|
A piece of one chromosome becomes attached to another non-homologous chromosome; usually reciprocal
|
|
Aneuploidy:
|
individuals have one extra or less chromosome (2n + 1 or 2n - 1)
Major cause of human reproductive failure; most human miscarriages are aneuploids |
|
Polyploidy:
|
individuals have three or more of each type of chromosome (3n, 4n)
Lethal for humans: 99% die before birth, newborns die soon after birth |
|
Down Syndrome:
|
Trisomy 21; mother’s age = risk factor
Mental impairment and a variety of additional defects Turner Syndrome: (XO; 98% spontaneous abortion) Survivors are short, infertile females with no functional ovaries, secondary sexual traits reduced, may be treated with hormones, surgery |
|
Klinefelter Syndrome: XXY condition
|
Results mainly from nondisjunction in mother (67%)
Phenotype is tall males; sterile or nearly so; feminized traits (sparse facial hair, somewhat enlarged breasts); treated with testosterone injections |
|
XYY Condition
|
Taller-than-average males; most otherwise phenotypically normal; once thought to be predisposed to criminal behavior, but studies now discredit
|
|
Watson-Crick Model
|
Experiments in the 1950s showed that DNA is the hereditary material – scientists then raced to determine the structure of DNA
1953 - Watson and Crick proposed that DNA is a double helix DNA consists of two nucleotide strands Strands run in opposite directions Strands are held together by hydrogen bonds between bases A binds with T, C with G Molecule is a double helix |
|
DNA to RNA to Proteins
|
DNA is a storage mechanism and represents the blueprint of the cell. Cells, however, are built from proteins and other molecules.
To make these “parts”, DNA is transcribed into RNA which serves as a “pattern” for fabricating new parts. RNA is translated (fabricated) into protein. RNA uses ribose sugars and Uracil [U] instead of Thymine |
|
Messenger RNA (mRNA):
|
carries instructions (pattern)
|
|
Ribosomal RNA (rRNA):
|
major component of ribosomes (factory)
|
|
Transfer RNA (tRNA):
|
delivers amino acids to ribosomes (worker)
|