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GENE 320 Test #2

Genetics Chapters 7-11 Human Heredity

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
Created by: tstrange