Intro to Development Flashcards
what describes the number of chromosomes and amount of DNA in a gamete?
23 chromosomes, 1N
what describes the number of chromosomes and amount of DNA in a somatic cell?
46, 2N
embryology
anatomy of human from conception to birth
conception
oocyte fertilized by sperm»_space; creases zygote
gamete
sex cells (egg and sperm)
which mature organs give rise to gametes?
ovaries and testies
what are gametes descendants of
primordial germ cells
where are gametes first observed?
umbilical vesicle (yolk sac)
what week do gametes migrate from yolk sac to gonad region?
week 4
what kind of membrane is an umbilical vesicle?
extraembryonic membrane
what happens to the chromosome number in meiosis?
reduced from 46»_space; 23
where are blood cells first found?
umbilical vesicle (yolk sac)
what process allows random exchange of maternal and paternal chromosomes between gametes?
meiosis
what is the result of meiosis II?
- 4 sperms (spermatogenesis)
- 1 mature ovum (oogenesis)
what are nonfunctional cells that eventually degenerate?
polar bodies produced from oocytes
what is the number of chromosomes in the cells?
ploidy
what is the amount of DNA?
N
when do chromosomes exist as single-chromatid chromosomes?
before DNA replication in S-phase of interphase
when do chromosomes exist as double-chromatid chromosomes?
after DNA replication
what separates the chromosome arms?
centromere
what are the shorter arms called?
P arm
what are the longer arms called?
q arms
what does the centromere attach to during cell division?
spindle fibers
how many chromosomes and DNA do somatic and primordial germ cells contain?
46 chromosomes
2N
during what process do single chromosomes undergo DNA replication to form duplicated chromosomes?
meiosis 1
what are inactivated X chromosomes called?
barr bodies
in which phase does the synapsis/pairing of 46 homologous duplicated chromosomes occur?
prophase meiosis 1
when does crossing over occur?
prophase meiosis 1
when does alignment of 46 duplicated chromosomes occur?
metaphase meiosis 1
when does disjunction occur?
anaphase meiosis 1
what is the result of meiosis 1?
23 duplicated chromosomes
2N
which process does not have a normal interphase?
meiosis II
which process does not have synapsis or crossing over?
meiosis II
where does alignment of 23 duplicated chromosomes occur?
metaphase plate during meiosis II
what occurs during meiosis II disjunction?
- centromeres split
- separation of 23 duplicated chromosomes into 23 single chromosomes
what is the result of meiosis II?
23 single chromosomes, 1N
which gametogenesis event is most likely in a chromosomal abnormality involving trisomy of chromosome 21?
disjunction
what is the name of gamete maturation?
spermatogenesis and oogenesis
47 chromosomes
trisomy
45 chromosomes
monosomy
what is the difference between spermatogenesis and oogenesis?
the timing of events during meiosis
when does oogenesis begin?
before birth
when does oogenesis end?
after puberty
where do some primordial germ cells get stranded during migration?
extragonadal sites
what can stray primordial germ cells give rise to?
tetratoma
what do the primordial germ cells differentiate into?
oogonia
what do oogonia give rise to by DNA replication?
oocytes
when are all primary oocytes formed by?
5th month
when are no oogonia present?
at birth
female has entire supply of primary oocytes at birth
what phase do primary oocytes remain dormant in from 5th month to puberty?
prophase 1 of meiosis
what happens to the primary oocyte with each cycle?
meiosis I»_space; forms 2 daughter cells (secondary oocyte and first polar body)
what does the secondary oocyte enter?
meiosis II
what does the first polar body do?
released and degenerates before ovulation
which hormones control the ovarian cycle?
- follicle stimulating hormone
- leteinizing horome
which hormone negatively feeds back and shuts down the GnRH for LH?
progesterone
when ovulation occurs, secondary oocyte chromosomes align at what?
metaphase plate
where do secondary oocyte remain arrested>
in uterine tube in metaphase meiosis II
when will oogenesis be completed?
fertilization
what is resulted from the secondary oocyte completing meiosis II?
- mature oocyte
- second polar body
where does fertilization occur?
uterine tube
3 phases of spermatogenesis
- spermatocytogenesis
- meiosis
- spermiogenesis
what is the production of primary spermatocytes from spermatogonia?
spermatocytogenesis
2 types of spermatogonia
A = undifferentiated stem cells, make more A or B
B = can make more B or go to meiosis to make primary spermatocytes
result of meiosis 1 primary spermatocytes
divide into secondary spermatocytes
when do primary spermatocytes divide into secondary spermatocytes?
during the S-phase before meiosis I
during S-phase before meiosis 1 what is the spermatocyte’s chromosome number?
- DNA doubles to 4N
- 46 chromosome stays same (diploid)
what do the secondary spermatocytes contain after meiosis I?
2N and 23 haploid chromosomes
what do secondary spermatocytes divide into during meiosis II?
4 spermatids
what is the chromosome number and DNA number for spermatids?
- 23 haploid chromosome
- 1N
what is the process when spermatids become elongated spermatozoa?
spermiogenesis
what is a large membrane-bound vesicle that covers the anterior 2/3 of the sperm nucleus?
acrosome formation
what is in the acrosome formation?
enzymes to penetrate the:
- corona radiata
- zona pellucida
union of sex cells or gametes is called what?
conception (results from fertilization)
what is the female gamete and where is it produced?
- egg (ovum)
- produced in ovary
what is the male gamete and where is it produced?
- sperm (spermatozoon)
- produced in seminiferous tubules
what is the process of making gametes called?
gametogenesis
what is the product of fertilization called?
zygote
where does fertilization occur?
Fallopian tube, oviduct, uterine tube
when does a child become capable of reproduction?
puberty (girls before boys)
what type of cell division do gametes ONLY undergo?
meiosis
what is the chromosome number of gametes?
haploid
what does a single chromosome consist of?
- 1 sister chromatid
- 2N
- 2 arms separated by centromere
what does a duplicated chromosome consist of?
- 2 sister chromatids
- 4N
- chromatids connected by centromere
what is the ploidy number for somatic cells?
haploid, 1N
how many autosomal and sex chromosomes do somatic cells have?
autosomal = 22 pairs
sex = 1 pair
how many autosomal and sex chromosomes do gametes have?
autosomal = 22 chromosomes
sex = 1 chromosome
how do female somatic cells ensure the same number of X genes to instruct the body
x-chromosome inactivation
when does X chromosome inactivation occur?
week 1
which maternal or paternal derived X chromosome is inactivated?
random
what is the separation of 46 duplicated chromosomes at anaphase without the centromeres splitting called?
disjunction
what is the cell division that makes 2 gametes, each with 23 duplicated chromosomes and 2N?
reduction division
which spermatogonia can enter meiosis?
B
what is the most likely cause of a sacrococcygeal teratoma?
some primordial germ cells came to a rest at an extragonadal site
