Practical #3 Flashcards
Character
A heritable feature of an organism that varies among individuals, features such as flower color in Mendel’s peas or freckles in humans
Trait
A variety or state of a character, such as a white flower color in peas or no freckles on a human.
Structural gene
The functional unit of heredity.
- It is found at particular locations on the chromosome, and the nucleotide sequence determines the primary structure of all
polypeptides and proteins.
Allele
An alternative form of a gene that occurs at the same location on homologous chromosomes.
- For example, the gene that codes for the ABO blood type has three alleles, A, B,
and O
Dominant allele
The allele expressed in a phenotype when a genotype is heterozygous.
- For example, in human blood groups the A and B alleles are dominant to the O allele. A
Recessive allele
The allele not expressed in the phenotype when the genotype is
heterozygous. Recessive alleles are only expressed when the genotype is homozygous.
Homozygous
A genotype with the same alleles for a gene on homologous chromosomes.
Heterozygous:
A genotype with different alleles for a gene on homologous chromosomes.
Genotype
The actual alleles present for a given gene on homologous chromosomes.
- Genotypes are expressed in letters.
Phenotype
The outward expression of a genotype, or what the trait looks like externally, or physically.
- Phenotypes are as described adjective words.
Codominant
A genetic condition that occurs when neither allele is dominant over another, but both are expressed in the phenotype
- For example, AB blood types
Internal fertilization
occurs when the sperm is transferred directly to the female’s body, and the secondary oocytes are fertilized inside of the female.
- The anatomy of the male is designed for the direct transfer of sperm to the female’s body
Viviparity
is when the embryos are retained in the female’s body.
What are the three parts of sperm?
the head, mid piece, and tail.
The head of the sperm contains what?
It contains the nucleus and is tipped with the acrosome.
What is the acrosome?
is composed of granular enzymes to dissolve the zona pellucida, which surrounds the secondary oocyte.
What does the midpiece of sperm contain?
It contains mitochondria for energy production.
What is the tail of sperm?
is a flagellum that propels the sperm cell.
Penis contains what?
erectile tissues.
Erectile tissues
tissues engorge with blood
during an erection.
What are the erectile tissues in the penis?
two corpora cavernosa and corpora spongiosum
Corpora cavernosa location
extends along the length of the penis and are located dorsally to the urethra. This tissue makes up
the bulk of the penis.
Corpora spongiosum location
extends along the length of the penis and is located beneath the corpora cavernosa. It encircles the urethra.
Testes contain what?
lobules
Lobules contain what?
seminiferous tubules and Interstitial cells
The lumen of the tubules
is lined with what?
seminiferous epithelium
Seminiferous epithelium function
produces the spermatids
Interstitial cells function
produce testosterone
Scrotum
an external sac of skin and smooth
muscle containing the testes.
What is the function of the smooth muscle of the scrotum?
raise and lower the scrotum to control the temperature of sperm.
Testes
These are the primary reproductive organs of males.
Testes function
They produce sperm and hormones like testosterone.
Epididymis
These are a series of convoluted ducts combining into a comma-shaped organ located on the
posterior surface of each testis.
Epididymis function
Spermatids differentiate into sperm and are stored in the
epididymis
Ductus deferens
- These ducts connect the epididymis with the ejaculatory ducts.
Ductus deferens fucntion
- They serve as sites for sperm
storage and conduct sperm to the ejaculatory ducts during an ejaculation.
Ejaculatory ducts
These are short ducts formed by the merging of the ducts from the seminal vesicle and the vas deferens.
Ejaculatory ducts function
They conduct sperm to the urethra
Urethra (males)
This is a large tube connecting the urinary bladder with the distal end of the penis.
Urethra (males) function
It conducts both sperm and urine, although not at the same time.
Seminal vesicles
- These sac-like glands are about 5 cm long.
- Their ducts empty into the ductus deferens.
- They produce about 60% of the semen’s volume.
Prostate gland
This is a gland surrounding the urethra where it exits
the bladder.
- It produces about 30% of the semen’s volume.
Bulbourethral gland
These are a pair of small glands located laterally on the urethra posterior to the prostate gland.
Bulbourethral gland function
They produce an alkaline mucus that lubricates the head of the penis.
Penis
The male copulatory organ that transfers the sperm directly to the female’s vagina.
Primordial follicles
These structures are composed of a primary oocyte surrounded by a single layer of squamous cells.
Primary follicles
These follicles are larger than the primordial follicles and the primary oocytes.
- They are surrounded by
several layers of cuboidal cells.
Secondary follicles
These follicles develop a fluid-filled cavity called the antrum that surrounds the secondary oocyte.
Antrum
a well-developed central chamber of the mature follicles
Granulosa cells
surround the outside of the antrum
Zona pellucida
is a glycoprotein gelatinous covering of the oocyte
Corona radiata
is a layer of cells that surround the
zona pellucida on the inside of the antrum
Corpus luteum
This is the glandular tissue that develops from the mature follicle after ovulation of the secondary
oocyte.
Corpus luteum function
It is important as a temporary endocrine gland in the secretion of hormones used to maintain pregnancy.
- If pregnancy does not occur, the corpus luteum degrades
Ovaries
These are the primary reproductive organs of females.
Ovaries location
They are located on the posterior wall of the female body cavity in the superior pelvic region.
Uterine tubes
These are small ducts that open into the body cavity near each of the ovaries.
- They extend from the
ovaries to the uterus.
Uterine tubes function
- The secondary oocyte or zygote travels from the ovaries through these tubes to the uterus.
- Fertilization most often occurs in the uterine tubes.
Infundibulum
The uterine tubes widen into a funnel-shaped structure that opens into the body cavity immediately next to the ovary.
- The opening of the infundibulum has long, thin, feather-like projections
called fimbriae.
Infundibulum function
These structures facilitate the
movement of the secondary oocyte into the uterine
tube.
Uterus
This is a thick muscular organ that lies between the uterine tubes and vagina.
- It is positioned posterior
to the urinary bladder and anterior to the rectum.
Endometrium
The innermost layer of the uterus and serves as the location of fetal
development.
Cervix
This structure is the inferior part of the uterus, immediately superior to the vagina.
Vagina
This is the tube that extends from the uterus to the outside of the female’s body.
- It is the female copulatory organ and is designed to receive the
male’s penis.
Vagina function
It also serves as the channel for
childbirth and menstruation.
Vulva
This is the female’s external genitalia.
What are the four parts of the vulva?
- mons pubis
- labia majora
- labia minora
- clitoris
Mons pubis
This is a pad of fatty tissue that is superior to the pubic symphysis.
- It serves to cushion the pubic
symphysis during intercourse.
Labia majora
These are a pair of thick folds of skin on either side of the vaginal opening.
- They partially protect the
vaginal opening and are involved in sexual arousal.
Labia minora
These are a pair of smaller folds of skin that lie beneath the labia majora and surround the urethral
and vaginal openings.
Clitoris
This is a small projection located between the labia majora just below the mons pubis.
- It is homologous to the glans penis in males and functions in sexual arousal.
The First Trimester
is the initial period of embryological and fetal development
What are the four major events during the first trimester?
cleavage, implantation, placentation, and embryogenesis
Zygote
When the secondary oocyte is fertilized it becomes a single cell
Blastomeres.
zygote undergoes a series of subdivisions that reduce the amount of cytoplasm in the cells.
Morula
The blastomeres subdivide for about three days to form a solid ball of cells
Blastocyst
The morula reaches the
uterus around day four and during the next two days, it develops into a hollow ball of cells
What structures are involved in cleavage?
- zygote
- blastomeres
- morula
- blastocyst
Blastocyst development
The blastocyst is composed of two cell layers.
- The outer layer develops into the placenta. The cells of the inner layer develop into the embryo.
Implantation
occurs when the blastocyst becomes embedded in the endometrium of the mother’s uterus.
Amniotic cavity
The separation yields a fluid- filled cavity
Gastrula
By the twelfth day, a third cell layer develops, and the blastocyst becomes a structure
What are the three germ layers during gastrulation?
ectoderm, mesoderm, and endoderm
The three germ layers then develop into what four extraembryonic membranes?
- Yolk sac
- Amnion
- Allantois
- Chorion
Yolk sac
This sac is a pouch formed from the endoderm and mesoderm.
- It is an initial site of blood cell
formation.
Amnion
- This membrane is formed from the ectoderm and mesoderm.
- It lines the inner surface of the amniotic cavity.
- The fluid contained within the cavity is called the amniotic fluid.
- The amnion and the amniotic
fluid surround and protect the growing embryo.
Allantois
This membrane is formed from the endoderm and mesoderm.
- It eventually gives rise to the urinary bladder.
Chorion
This membrane is formed from the mesoderm and the outer cell layer of the blastocyst.
- The chorion differentiates into the fetal portion of the placenta as
the embryo enlarges.
Placentation
is the development and differentiation of the fetal and maternal portions of the placenta.
Chorionic villi
The chorion develops finger-like projections
Lacunae
small chambers in the maternal placenta
Umbilical cord
contains two umbilical arteries and one umbilical vein.
Embryogenesis
is the differentiation of the body of the embryo and the rudimentary development of the organ systems.
What is the name of chart used to track the inheritance of traits through multiple generations?
pedigree
What type of cross is used when only one characteristic is being looked at?
monohybrid cross
