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ch.29 development &
inheritance
| Question | Answer |
|---|---|
| is the study of events from fertilization of a secondary oocyte to formation of an adult organism | developmental biology |
| is the study of development from the fertilized egg through the 8th week | embryology |
| lasts from the 9th week until birth | fetal period |
| a series of events that begins from conception (fertilization) until birth ; lasts about 38 weeks | pregnancy |
| the 4 events that happen in the first week of development | 1. fertilization 2. cleavage of zygote (cell division) 3. blastocyst formation 4. implantation |
| this first event usually occurs in the fallopian tube 12-24 hours after ovulation | fertilization |
| sperm can remain viable for about __ hours after deposition in the vagina | 48 |
| a secondary oocyte is viable for only about ___ hours after ovulation | 24 |
| pregnancy is most likely to occur if intercourse takes place during a 3 day window - from __ days before ovulation to ___ day after ovulation | 2, 1 |
| the fusion of sperm with secondary oocyte | syngamy |
| for a zygote to form after syngamy (sperm cell enters a secondary oocyte), the secondary oocyte must complete ___ | meiosis II |
| the nucleus in the head of the sperm develops into the | male pronucleus |
| the nucleus of the fertilized ovum develops into the | female pronucleus |
| the male and female pronuclei must fuse to restore the ___ number of 46 chromosomes | diploid (2n) |
| ___ twins are produced by fertilization of 2 secondary oocytes | fraternal (aka dizygotic) |
| __ twins are produced by fertilization of 1 ovum that separates into 2 embryos, usually within 8 days of fertilization | identical (aka monozygotic) |
| the second event within the first week of development | cleavage of the zygote |
| rapid mitotic cell divisions of the zygote | cleavage |
| the first division of the zygote begins about __ hours after fertilization | 24 |
| additional/successive cleavages eventually produce a SOLID sphere of cells called the ___ and is about the same size as the original zygote | morula |
| event 3 in the first week of development | blastocyst formation |
| the morula continues to divide and moves toward uterus; when morula arrives @ uterus, its cells rearrange to form a HOLLOW sphere filled with a fluid called | uterine milk |
| once the blastocyst cavity is formed, the developing mass is called the | blastocyst |
| though it now has hundereds of cells, the blastocyst is still about the same size as the original ___ | zygote |
| the 4th event in the first week of development; the attachment of a blastocyst to the endometrium | implantation |
| shedding of the __ __ is necessary for implantation to occur | zona pellucida |
| about 6 - 7 days after fertilization, the blastocyst attaches to the ___ in a process called implantation | endometrium |
| implantation usually occurs in either the posterior portion of the ___ or the body of the ___ | fundus, uterus |
| following implantation, the endometrium is now known as the | decidua |
| about 8 days after fertilization, the trophoblast (outer layer of cells that form the blastocyst)divides into 2 layers and become part of the ___ | chorion (embryonic portion of the placenta) |
| ___ rescues the corpus luteum from degeneration and sustains its secretion of progesterone and estrogens | hCG |
| during the ___ week of development, 3 primary germ layers are established and lay the groundwork for ___ development | third, organ |
| the 3 primary germ layers are | endoderm, mesoderm, and ectoderm |
| the epithelial lining of many hollow internal organs and glands (ie GIT, resp tract) | endoderm |
| loosely organized CT that gives rise to all skeletal and cardiac muscle tissue, most smooth muscle, bones and the peritoneum | mesoderm |
| develops into the epidermis of skin and the nervous system | ectoderm |
| by the beginning of the 12th week the placenta has 2 distinct parts: | a fetal portion formed by teh chorionic villi and a maternal portion |
| from 9 weeks to term (birth) is called the __ period | fetal |
| during the fetal period, ___ and ___ that developed during the embyronic period grow and differentiate | tissues and organs |
| half of the full-term weight is added in the last ___ months of gestation | 2.5 |
| any agent or influence that causes developmental defects in the embryo or fetus | teratogens |
| 4 examples of teratogens | chemicals and drugs; cigarette smoking; irradiation; pesticides |
| during the first 3 -4 months of pregnancy, the corpus luteumin the ovary continues to secrete __ and ___ which maintain the lining of the uterus during pregnancy | estrogen and progesterone |
| hCG from ___ stimulates the corpus luteum to continue producing estrogen and progesterone | chorion |
| by about __ weeks, hCG is no longer needed because the chorion begins to secrete these hormones (instead of the corpus luteum) | 6 |
| a hormone that increases the flexibility of the pelvis and helps dilate the cervix during delivery | relaxin |
| a hormone that prepares mammary glands for lactation and reaches maximum levels after 32 weeks | hCS (human chorionic somatomammotropin) |
| the hormone thought to be the "biological clock" that establishes delivery date (timing of birth) | CRH (corticotropin releasing hormone) |
| by the end of the __ month the uterus occupies most of the pelvic cavity of the mother | 3rd |
| toward the end of a full term pregnancy, ___ nearly fills the abdominal cavity | uterus |
| pressure on the stomach may cause ___ of contents of stomach into esophagus | reflux |
| in the pelvic cavity, compression of the ___ and ___ occurs | ureters and urinary bladder |
| to meet additional demands of growing fetus, all of the following maternal cardiovascular factors occur | cardiac output, stroke volume, and heart rate |
| maternal changes also include an ___ in total body oxygen; difficulty breathing may occur due to compression of ___ | increase, thorax |
| maternal changes also include an increased ___ (to meet nutritional demands of fetus) and changes in ___ color and pliability of reproductive organs | appetite, skin |
| hormone that promotes milk synthesis | prolactin |
| hormone that causes milk "let-down" | oxytocin |
| the passage of hereditary traits from one generation to the next | inheritance |
| refers to genetic makeup; the DNA sequence of gene for a trait | genotype |
| refers to the physical or outward expression of a gene | phenotype |
| alternative forms of a gene that code for the same trait | allele |
| an allele that dominates or masks the presence of another allele and is fully expressed | dominant allele |
| the allele whose presence is completely masked and the trait it controls is called a recessive trait | recessive allele |
| the nuclei of all human cells (except gametes) contain ___ pairs of chromosomes - the diploid number (2n) | 23 |
| one chromosome in each pair came from the __ and the other came from the ___ | mother, father |
| each chromosome of the 2 homologues (mother, father) contains ___ for the same trait | genes (alleles) |
| a person with the same alleles on homologous chromosomes (PP or pp) is said to be ___ for the trait | homozygous |
| an individual with different alleles on homologous chromosomes (Pp) is said to be __ for the trait | heterozygous |
| allele symbolized by P | dominant allele |
| allele symbolized by p | recessive allele |
| only the homozygous recessive epxresses the trait pp -true or false | true |
| the variations on dominant recessive inheritance | 1. Incomplete dominance (ie Sickle Cell disease) 2. Mulipile Allele inheritance (ie ABO blood groups) 3. Complex inheritance |
| although a single individual inherits only 2 alleles for each gene, some genes may have more than 2 alternative forms. this is called: | multiple-allele inheritance |
| the four blood types (phenotypes) of the ABO group - A, B, AB, and O - result from the inheritance of 6 combinations of 3 different alleles of a single gene called | I gene |
| most inherited traits are not controlled by one gene, but instead by the combined effects of 2 or more genes, referred to as ___ | polygenic inheritance |
| the combined effects of many genes and environmental factors (ie full height of a person may not be reached due to disease or malnutrition) | complex inheritance |
| examples of ___ traits are skin color, height, hair color, metabolic rate, and eye color | complex |
| the genetic makeup of an organism is called its __; the traits expressed are called its ___ | genotype; phenotype |
| __ genes control a particular trait; expression of ___ genes is masked by dominanct genes | dominant, recessive |
| in ___ dominance, neither member of an allelic pair dominates | incomplete |
| in __inheritance, genes have more than 2 alternative forms; an example is the inheritance of the ABO blood groups | multiple-allele |
| in ___ inheritance, a trait such as eye or skin color is controlled by the combined effects of 2 or more genes and my be influenced by environmental factors | complex |
| red-green color blindness, hemophilia, and juvenile diabetes result from ___ genes located on the ___ chromosome | recessive, X |
| sex-linked traits occur primarily in ___ because of the absence of any counterbalancing dominanct genes on the Y chromosome | males |
| red-green color blindness due to deficiency of either ___ or ___ sensitive cones in retina (red and green are seen as the same color) | red or green |
| females may express the sex-linked trait if 2 ___ people produce an offspring, or a color blind male and a carrier ___ produce an offspring | colorblind; female |
| ___ recessive females may show sex-linked trait | homozygous |
| hormone produced by the placenta is thought to establish timing of birth and stimulates secretion of cortisol by the adrenal gland | CRH (corticotropin releasing hormone) |
| hormone that contributes to breast development, protein anabolism, and catabolism of glucose and fatty acids | hCS (human chorionic somatomammotropin) |
| pregnancy is maintained by the hormones: | hCG, estrogens and progesterone |
| hormones produced by the ___ are responsible for maintaining the pregnancy during the first 3-4 months | corpus luteum |
| the hormone responsible for preventing degeneration of the corpus luteum is ___ produced by the trophoblast | HCG |
| the germ layers responsible for development of the following structures: muscle, bone, and peritoneum: ____; nervous system and epidermis: ____; epithelial linings of respiratory tracts and GIT: ___ | mesoderm; ectoderm; endoderm |
| maternal changes that occur during pregnancy | altered pulmonary function; weight gain; edema and possible varicose veins; co, hr, sv increase; total body oxygen increases; increased appetite; changes in skin color and pliability of repro organs |
| fluid filled sphere of cells that enters teh uterine cavity | blastocyst |
| cells produced by cleavage | blastomeres |
| the outer covering of cells of the blastocyst | trophoblast |
| membrane derived from trophoblast | chorion |
| early division of the zygote | cleavage |
| a solid sphere of cells still surrounded by the zona pellucida | morula |
| event in which differentiation into the 3 primary germ layers occur | gastrulation |
| embryonic development of structures that will become the nervous system | neurulation |
| result of the fusion of female and male pronuclei | zygote |
| stimulate the corpus luteum to continue production of progesterone and estrogens | hCG |
| increases the flexibility of the pubic symphysis and helps dilate the uterine cervix during labor | relaxin |
| secreted by the placenta; helps establish timing of birth and increases the secretion of cortisol for fetal lung maturation | CRH |
| helps prepare mammary glands for lactation; regulates certain aspects of maternal and fetal metabolism | hCS |
| stimulate uterine contractions; responsible for milk letdown | oxytocin |
| promotes milk synthesis and secretion; inhibited by progesterone during pregnancy | prolactin |
| the penetration of a secondary oocyte by a single sperm cell | syngamy |
| the control of inherited traits by the combined effects of many genes | polygenic inheritance |
| the 2 alternative forms of a gene that code for the same trait and are at the same location on homologous chromosomes | alleles |
| inheritance based on genes that have more than 2 alternative forms; an example is the inheritance of blood type | multiple-allele inheritance |
| referes to an individual with different alleles on homologous chromosomes | heterozygous |
| traits linked to the X chromosome | sex-linked inheritance |
| neither member of the allelic pair is dominant over the other | incomplete dominance |
| refers to how teh genetic makeup is expressed in the body; the physical or outward expression of a gene | phenotype |
| a homozygous dominant, homozygous recessive, or heterozygous genetic makeup; the actual gene arrangement | genotype |
| refers to a person with the same alleles on homologous chromosomes | homzygous |
| an allele that masks the presence of another allele and is fully expressed | dominant trait |
Created by:
girlvo