Term | Definition |
---|---|
Zygote | The fertilized egg that develops into the new individual |
Sperm | Male gamete |
Oocyte | Female gamete |
Gametes | Unfertilized germ cells |
Gonads | Organs where gametes are produced |
Testes | Male gonads that produce spermatozoa and sex hormones |
Ovaries | Female gonads that produce oocytes and female sex hormones |
Scrotum | Pouch of skin outside the male body that contains the testes |
Seminiferous tubules | Small, tightly coiled tubes within the testes where sperm are produced |
Spermatocytes | Diploid cells that undergo meiosis to form haploid spermatids |
Epididymis | Where sperm is stored |
Vas deferens | A duct connected to the epididymis, which sperm travels through |
Ejaculatory duct | A short connector from the vas deferens to the urethra |
Urethra | A tube that passes the bladder and opens to the outside. Functions as urine and, in males, sperm transport. |
Seminal Vesicles | Glands that release fructose and prostaglandins into the semen |
Prostaglandins | Locally acting chemical messengers that stimulate contraction of the female reproductive system to assist in sperm movement |
Prostate gland | A gland that secretes a milky, alkaline fluid that neutralizes acidic vaginal secretions and enhances sperm viability |
Bulbourethral glands | Glands that secrete a mucous- like substance that provides lubrication for intercourse |
Semen | A mixture of sperm and various glandular secretions containing 5% spermatozoa |
Follice | A developing egg surrounded by an outer layer of follicle cells, contained in the ovary |
Ovulation | The release of a secondary oocyte from the follicle; usually occurs monthly during a female's reproductive lifetime |
Oviduct | A duct with fingerlike projections partially surrounding the ovary and connecting to the uterus. Also called fallopian or uterine tube |
Uterus | A hollow, pear shaped muscular organ where a fertilized egg will developed |
Endometrium | The inner lining of the uterus that is shed at menstruation if fertilization has not occurred |
Cervix | The lower neck of the uterus opening into the vagina |
Vagina | The opening that receives the penis during intercourse and also serves as birth canal |
Oogenesis | Process of oocyte production |
Oogonia | Cells that produce primary oocytes by mitotic division |
Fertilization | The fusion of two gametes to produce a zygote |
Blastocyst | The developmental stage at which the embryo implants into the uterine wall |
Inner cell mass | A cluster of cells in the blastocyst that gives rise to the embryonic body |
Trophoblast | The outer layer of cells in the blastocyst that gives rise to the membranes surrounding the embryo |
Chorion | A two- layered structure formed in the trophoblast |
Teratogen | Any physical or chemical agent that brings about an increase in congenital malformations. Ex. Alcohol, radiation, viruses, and chemicals. |
Sex ratio | The proportion of males to females, which changes throughout the life cycle. The ratio is close to 1:1 at fertilization, but the ratio of females to males increases as the population ages |
Sex determination is determined when? | Chromosomal sex us determined at fertilization. Sexual differentiation begins in the seventh week and is influenced by a combination of genetic and environmental factors. |
SRY | A gene, called the sex- determining region of the Y, located near the end of the short arm of the Y chromosome, plays a major role in causing the undifferentiated gonad to develop into a testis |
Testosterone | A steroid hormone produced by the testis; the male sex hormone |
Mullerian inhibiting hormone (MIH) | A hormone produced by the developing testis that causes the breakdown of Mullerian ducts in the embryo |
Androgen insensitivity | An X-linked genetic trait that cause XY individuals to develop into phenotypic females |
Pseudohermaphroditism | An autosomal genetic condition that causes XY individuals to develop the phenotypic sex of females |
Dosage compensation | A mechanism that regulates the expression of sex-linked gene products |
Barr body | A densely staining mass in the somatic nuclei of mammalian females. An inactivated X chromosome |
Lyon hypothesis | The proposal that dosage compensation in the mammalian females is accomplished by partially and randomly inactivating one of the two X chromosomes |
X inactivation center (Xic) | A region on the X chromosome where inactivation begins |
Sex- influences traits | Traits controlled by autosomal genes that are usually dominant in one sex but recessive in other sex |
Pattern baldness | A sex- influenced trait that acts like an autosomal dominant trait in males and autosomal recessive in females. |
Sex- limited genes | Loci that produce a phenotype in only one sex |
Imprinting | A phenomenon in which expression of gene depends on whether it is inherited from the mother or father |
DNA | Macro- molecular component to cells that encodes genetic information |
Friedrich Miescher | 1860's, First person to isolate and purify a cellular organelle- nuclei |
Griffith | Ability to cause pneumonia is a genetic trait that can be passed from one strain of bacteria to another |
Transformation | The process of transferring genetic information between cells by DNA molecules |
Transforming factor | The molecular agent of transformation; DNA |
Avery | 1944 1. Only DNA transfers and carries heritable information from one bacterial strain to another strain. 2. DNA controls the synthesis. Transfer of DNA also results in the transferring of the ability to synthesize a specific gene product. |
Alfred Hershey and Martha Chase | Grew phages with radioactive phosphorus, making DNA radioactive. Only phage DNA |
Watson and Crick | 1953, Structure of DNA used Xray crystallography |
Rosalind Franklin& Maurice Wilkins | X-ray crystallographic pictures of DNA |
Erwin Chargaff | Rule of Base Composition of DNA A=T and G=C |
RNA functions | Found in nucleus and cytoplasm. Transfers genetic information, participates in protein synthesis , component of ribosomes. |
Chromatin | The complex of DNA and proteins that makes up a chromosome |
Histones | DNA binding proteins that help compact an fold DNA onto chromosomes |
Nucleosome | A bead-like structure composed of histones wrapped with DNA |
Semiconservative replication | A model of DNA replication that provides each daughter molecules with one old strand and one newly synthesized strand. DNA replicates in this fashion. |
DNA polymerase | An enzyme that catalyzes the synthesis of DNA using a template DNA strand and nucleotides |
Prion Diseases | Abnormally folded prions cause the normal proteins in the body to refold into a new, infectious three dimensional shape that kills cells of the brain and nervous tissue, forming holes in the brain tissue |
Alkaptonuria | Black- urine disease, autosomal recessive |
Garrod | Worked with Alkaptonuria, inborn errors in metabolism |
Beadle and Tatum | Neurospora, showed mutation of a single gene caused loss of activity in a specific enzyme, causing mutant phenotype. |
Crick and Brenner | Genetic code consist of a linear series of three nucleotides and each triplet specifies and amino acid |
Stop codons | UAA, UGA, UAG |
AUG codon | Encodes information for the amino acid methionine and serves as start codon |
mRNA | A single stranded complementary copy of the nucleotide sequence in a gene |
Transcription | Transfer of genetic information from the base sequence of DNA to the base sequence of RNA, mediated by RNA synthesis -in nucleus |
Translation | Conversion of information encoded in the nucleotide sequence of an mRNA molecule into the linear sequence of amino acids in protein – in cytoplasm |
Three stages of transcription &translation | Initiation, Elongation, and Termination |
Initiation 1 | RNA polymerase binds to promotor region. After polymerase is bound, the two strands of the DNA in the gene unwind, exposing DNA strand that will be a template for RNA synthesis. |
Promotor Region | A region of a DNA molecule to which RNA polymerase binds and initiates transcription. |
Elongation 1 | RNA polymerase links RNA nucleotides together, forming a growing RNA molecule called an mRNA transcript. |
Terminator Region | The nucleotide sequence at the end of a gene that signals the end of transcription |
Termination 1 | When the RNA polymerase reaches the terminator region, it falls off the DNA strand, the mRNA molecule is released, the DNA strands re-form a double helix, and transcription is terminated. |
Introns | DNA sequences present in some genes that are transcribed but are removed during processing and therefore are not present in mature mRNA |
Exons | DNA sequences that are transcribed, joined to other exons during nRNA processing, and translated into the amino acid sequence of a protein. |
Cap | A modified base (guanine nucleotide) attached to the 5' end of eukaryotic mRNA molecules- helps to attach mRNA to ribosomes during translation |
Poly-A tail | A series of Adenine nucleotides added to the 3' end of mRNA molecules |
tRNA | A small RNA molecule that contains a binding site for a specific type of amino acid and has three base segment know as an anticodon that recognizes a specific base sequence in mRNA |
Site of protein synthesis | Ribosomes |
Anticodon | A group of three nucleotides in a tRNA molecule that pairs with a complementary codon in an mRNA molecule |
Initiation 2 | mRNA and a tRNA form an initiation complex (mRNA, tRNA, and small ribosomal subunit) AUG to UAC anticodon |
Elongation 2 | Begins when amino acids are added to the growing protein. |
P site vs A site | tRNA carrying methionine binds to P site. Elongation begins when tRNA binds to mRNA codon next to the initiation codon in the A site |
Chaperones | guide polypeptide folding |
Fates of polypeptide | 1. Made on outer ER, go to inner ER where they are folded, modified, and moved to Golgi apparatus for packaging and secretion from the cell at the plasma membrane or incorporation into lysosomes 2. If made on ribosomes, are folded and used in cell |
Proteome | The set of proteins present in a particular cell at a specific time under a particular set of environmental conditions |
Protein folding diseases | Alzheimers, MPS VI. |
Prion disease examples | Creutzfeldt- Jakob, Gerstmann- Staussler, Fatal familiar insomnia in humans. Bovine Spongiform Encephalopathy or Madcow in bovine. |
Order to phenotype | Gene–> mRNA –> protein –> phenotype |
Galactosemia | Autosomal recessive disorder caused by inability to break down galactose. Causes cataracts and mental retardation |
Sickle Cell | From glutamate to valine in position six in beta globin- Defect in transport protein |
Pseudogenes | Nonfunctional genes that are closely related by DNA sequence to functional genes present somewhere else in genome |
Hemoglobin variants | Involve change to the amino acid sequence of globulin polypeptides |
Thalassemias | Imbalance in alpha or beta globulin synthesis |
Alpha and Beta thalassmias | Alpha- reduced or absent Beta- affects synthesis |
Ecogenetics | The study of genetic variation that affects responses to environmental chemicals |
Mutation rate | The number of events that produce mutated alleles per locus per generation |
Why do genes have different mutation rates? | Size of gene, nucleotide sequence, spontaneous chemical change |
Radiation | The process by which EM energy travels through space or a medium such as air |
Ionizing radiation | Radiation that produces ions during interaction with other matter, including molecules in cells |
Background radiation | Radiation in the environment that contributes to radiation exposure |
Rem | The unit of radiation exposure used to measure radiation damage in humans. It is the amount of ionizing radiation that has same effect as a standard amount of x-rays |
Milirem | 1 rem is equal to 1000 milirems |
Base Analog | A purine or pyrimidine that differs in chemical structure from those normally found in DNA or RNA |
Nucleotide substitutions | Mutations that involve replacing one or more nucleotides in a DNA molecule with other nucleotides |
Frameshift mutations | Mutational events in which a number of bases (other than multiples of three) are added or removed from DNA |
Missense mutations | Mutations that cause the substitution of one AA for another in a protein |
Sense mutations | Mutations that change a termination codon into one that codes for an amino acid- produce elongated proteins |
Nonsense mutations | Mutations that change an amino acid specifying a codon to a termination codon |
Trinucleotide repeats | A form of mutation associated with the expansion in copy number of a nucleotide triplet in or near a gene |
Allelic expansion | Increase in gene size caused by an increase in the number of tri-nucleotide sequences |
Anticipation | Onset of a genetic disorder at earlier ages with increasing severity in successive generations |
Thymine dimer | A molecular lesion in which chemical bonds form between a pair of adjacent thymine bases in a DNA molecule |
Genomic imprinting | phenomenon in which the expression of a gene depends on whether it is inherited from the mother or the father. Also known as genetic or parental imprinting |
Uniparental Disomy | A condition in which both copies of a chromosome are inherited from one parent |