genetics test 1
cellular activities & abnormalities underlie our inherited traits, quirks, & illness understanding genetic diseases can suggest… ways to treat the condition our bodies include more than ____ cell types 290 Somatic (body) cells are diploid Diploid an organism or cell having two sets of chromosomes or twice the haploid number sperm and egg cells are haploid Haploid an organism or cell having only one complete set of chromosomes ____ _____ can both replicate themselves & give rise to differentiated cells stem cells how many sets of chromosomes do gametes have for fertilization? 1 Meiosis sex cell process Prokaryote A unicellular organism that lacks a nucleus and membrane bound organelles Eukaryote A cell that contains a nucleus and membrane bound organelles Types of human tissue epithelial, connective, muscle, nervous muscle tissue function movement epithelial tissue functions protection; lines organs; skin is made of this nervous tissue function internal communication connective tissue functions supports & transports 3 domains of life Bacteria, Archaea, Eukarya Archaea unicellular prokaryotes Bacteria unicellular prokaryotes; have this when we have an infection Eukarya unicellular and multicellular eukaryotes Biomolecules
carbohydrates, lipids, proteins, nucleic acids
Carbohydrate examples
sugars, starches
Carbohydrates function
energy, structure
Lipids examples
fats and oils
Lipids function
long term energy storage; membranes, hormones
Proteins examples
myosin, collagen
Proteins function
build, maintain and repair tissue in body; enzymes, structure
nucleic acids examples
DNA and RNA
nucleic acids functions
store and transmit genetic info
longest phase of the cell cycle
Interphase
Mitosis
cell division
Apoptosis
programmed cell death
cell cycle
g phase - gap for growth, s phase - DNA synthesis, m phase - mitosis, cytokinesis - cell division
nuclear division
the division of a cell's nucleus, as in mitosis and meiosis
parts of nuclear division
prophase, metaphase, anaphase, telophase, cytokinesis
Interphase
prepares for cell division, replicates DNA & subcellular structures, composed of g1, s, & g2
Cytokinesis
division of the cytoplasm
chromosomes are replicated during the ___ phase prior to mitosis
s
result of the replication of chromosomes is…
2 sister chromatids held together at the centromere
checkpoints in the cell cycle ensure that…
mitotic events occur in the correct sequence
many types of cancer result from ____ _________
faulty checkpoints in the cell cycle
Telomeres
Repeated DNA sequences at the ends of eukaryotic chromosomes.
Where are telomeres located?
End of each chromosome
how many telomeres are lost after each cell division?
50-200
What do shortened telomeres signal?
aging
what do sperm, egg, bone marrow, & cancer cells produce?
telomerase that prevent shortening of telomeres
cancer can result from…
too much mitosis, too little apoptosis
2 types of cell to cell communication
signal transduction & cellular adhesion
signal transduction pathway
transmits signals from outside the cell & transmits them inward
cellular adhesion
precise sequence of interactions among proteins that help connect cells
example of cellular adhesion
inflammation
3 types of cellular adhesion molecules (CAMS) help guide _____ ______ _____ to the injured area
white blood cells (WBCs)
stem cells
unspecialized cells that are able to renew themselves for long periods of time by cell division
stem cell divides by ______
mitosis
stem cells produce…
daughter cells that retain the ability to divide
progenitor cells
cells of the ventricular zone that divide; do not have the capacity of self-renewal
all cells in the human body descend from stem cells via…
mitosis & differentiation
cells differentiate down cell lineages by…
differential gene expression
stem cells are present throughout life & provide…
growth & repair
stem cells are described in terms of their…
developmental potential
3 types of stem cells
totipotent, pluripotent, multipotent
totipotent stem cell
embryonic stem cell that is capable of differentiating into any and all cells of the body; enabling the full development of an organism
embryonic cells within the first couple of cell division after fertilization are the only cells that are _________
totipotent
pluripotent stem cells
Stem cells that can become almost all types of tissues and cells in the body.
multipotent stem cells
stem cells that can become a limited number of types of tissues and cells in the body
3 sources of stem cells
- embryonic stem cells
- induced pluripotent stem cells
- adult stem cells
embryonic stem cells
created in a lab dish using an embryo
induced pluripotent stem cells
somatic cells reprogrammed to differentiate into any of several cell types
adult stem cells
tissue-specific or somatic stem cells
4 ways stem cells are used
- discovery & development of drugs
- observing the earliest sign of disease
- treatment of disease via implants & transplants
- stimulating stem cells in the body via the introduction of reprogramming proteins
90% of cells in the human body are…
microorganisms
different body parts house different communities of ______
microbes
genes interact with the _______ & with environmental factors to mold most traits
microbiome
My older sister is 6 ft. tall so I know I will be too.
genetic determinism
you have 22 pairs of them
autosomes
ex: the human stomach is made of muscle, epithelial, & nervous tissue
differentiation
one of these will visually show an extra chromosome
karyotypes
in humans, 20,325 DNA sequences that encode protein
exome
the variants of a gene
alleles
one allele only must be present to be expressed
dominant
both alleles must be present to be expressed
recessive
x & y
sex chromosomes
you do not have one of these, but a population does
gene pool
at least 50 genes control blood pressure but obesity & alcohol consumption do too
multifactorial
6 fingers & six toes (polydactyly)
phenotype
X^cX^c
genotype
a change in DNA
mutation
the helix called the "secret of life"
deoxyribonucleic acid
unspecialized cells with different fates
stem cells
an organism's entire DNA sequence of information
genome
addresses the "personal side" of genetics
bioethics
a combo of DNA & protein; appear threadlike
chromosomes
this field helps us compare ourselves to other species
genomics
basic unit of heredity; made of DNA
genes
can show several generations of inheritance
pedigree
contains uracil instead of thymine
ribonucleic acid
bioethics
ethical genetics
gametes form from special cells called
germline cells
germline cells
eggs or sperm cells that carry genetic instructions to organisms of the next generation
meiosis is…
cell division that halves the chromosome number
homologous pairs
have the same genes in the same order but carry different alleles, or variants, of the same gene
Gametes
sex cells that are haploid
somatic cells
body cells; diploid for each chromosome
absence of meiosis could lead to genetically
overloaded cells
what mixes up trait combinations?
meiosis
meiosis provides ______ ______ which can enable a population to survive an environmental challenge
genetic diversity
meiosis consists of _ divisions
2
meiosis I is called
the reduction division
Meiosis I reduces
number of chromosomes from 46 to 23
Meiosis II is called
the equational division
meiosis II produces
4 cells from the 2 produced in meiosis I
each cell division contains
prophase, metaphase, anaphase, & telophase
in prophase I…
a spindle forms; homologs pair up & undergo crossing over; chromosomes condense; synapsed chromosomes separate but remains attached at a few points
in metaphase I…
Homologous pairs align along the equator of the cell; random alignment of chromosomes causes independent assortment of the genes that they carry
in anaphase I & telophase I…
homologs separate in anaphase I; move to opposite poles by telophase I; centromeres of each homolog in meiosis I remain together
Meiosis II
sister chromatids separate; prophase ii, metaphase ii, anaphase ii, telophase ii -> resulta in 4 nonidentical haploid daughter cells
in prophase II & metaphase II…
-chromosomes are again condensed and visible
-chromosomes align along the equator of the cell
in anaphase II & telophase II…
-centromeres divide
-newly formed, unreplicated chromosomes move to opposite poles
-nuclear envelope reforms
-separate into individual cells
results of meiosis
4 haploid cells, each carry a new assortment of genes and chromosomes that hold one copy of the genome
Comparison of Mitosis and Meiosis
Mitosis
- one division
- two daughter cells per cycle
- daughter cells genetically identical
-chromosome # of daughter cells same as that of parent cell
- occurs in somatic cells
- occurs throughout life cycle
- used for growth, repair, & asexual reproduction
meiosis
- two divisions
- 4 daughter cells per cycle
- daughter cells genetically different
- chromosome # of daughter cells half that of parent cell
- occurs in germline cells
- in humans, completes after sexual maturity
- used for sexual reproduction, producing new gene combinations
Spermatogenesis
Formation of sperm
Oogenesis
begins with a diploid oogonium; in meiosis I, primary oocyte divides unequally forming a small polar body & a large secondary oocyte; in meiosis II, the secondary oocyte divides to form another polar body & a mature ovum
unlike spermatogenesis, oogenesis is…
discontinuous process; oocytes arrest at prophase I until puberty; after puberty, meiosis I continues in one or several oocytes each month but halts again at metaphase II
meiosis is only completed if the ovum is________
fertilized
a prenatal human is considered __ ______ for the first 8 weeks
an embryo
from the start of the ninth week until birth, a prenatal human is called _ _____
a fetus
Fertilization
union of sperm & oocyte; 100's of million sperm in vagina can live 72 hours, ovum can only be fertilized 12-24 hours after ovulation; in the female sperm are capacitated & drawn to the oocyte; acrosomal enzymes aid sperm penetration; chemical & electrical changes in the oocyte surface block entry of more sperm; 2 genetic packages meet & merge, forming a zygote
Cleavage
a period of frequent mitotic divisions resulting early cells called blastomeres; developing embryo becomes a solid ball of 16+ cells called a morula; the ball of cells hollows out to form a blastocyst
blastocyst
hallow ball of cells filled with fluid; inner cell mass develops into the embryo; trophoblasts secrete human chorionic gonadotropin that prevents menstruation - a sign of pregnancy; implantation in the uterus occurs around day 7
embryo formation
the primary germ layers form in the second weeks after fertilization: ectoderm, mesoderm, endoderm; this 3 layer structure is the gastrula; cells in each layer begin to form specific organs controlled by homeotics; here genes can be silenced by methyl (CH3)
Ectoderm
outermost germ layer
Mesoderm
middle germ layer
Endoderm
innermost germ layer
structures that support & protect the embryo
chorionic villi,
yolk sac,
allantois,
umbilical cord,
amniotic sac
by __ weeks the placenta is fully formed
10
fertilized ovum summary
12-24 hours following ovulation; oocyte fertilized, zygote has 23 pairs of chromosomes & is genetically distinct
cleavage summary
30 hours-3 day; mitosis increases cell #
morula summary
3-4 da; solid ball of cells
blastocyst summary
5 day-2 week; hollowed ball forms trophoblast (outside) & inner cell mass, which implants & flattens to form embryonic disc
gastrula summary
end of 2 week; primary germ layers form
dizygotic twins
fraternal twins
in dizygotic (fraternal) twins…
2 sperm fertilize 2 oocytes; same genetic relationship as 2 siblings
monozygotic twins
identical twins
monozygotic (identical) twins…
arise from 1 fertilized ovum; 3 types of MZ twins can form depending on when the fertilized ovum or very early embryo splits; embryo divides between days 13-15
conjoined twins
1 in 50,000-100,000 pregnancies
vanishing twins
Occurs when one twin fails to develop and is absorbed
Organogenesis
formation of 3 germ layers & organs
during week 3, a band called the primitive streak appears
along the back of the embryo
by week 8, all organs present in the newborn have
begun to develop
during week 8, embryo is sensitive to ______ & ______
chemicals & virsuses
fetal period (9 weeks to birth)
body proportions approach a newborn; bone replaces cartilage; nerve & muscle functions become coordinated; sex organs become more distinct; week 12 - sucks thumb, kicks, has beginnings of teeth
When is sex determined?
conception
what matures last in a fetus?
digestive & respiratory systems
odds of having a miscarriage in the U.S.
10%
homologous chromosomes pair up & form tetrad
prophase I
spindle fibers move homologous chromosomes to opposite sides
anaphase I
nuclear membrane forms, cytoplasm divides, 4 daughter cells
telophase II
chromosomes line up along the equator, not in homologous pairs
metaphase II
crossing-over occurs
prophase I
chromatids separate
anaphase II
Homologs line up along equator
Metaphase 1
cytoplasm divides, 2 daughter cells are formed
telophase I
metaphase I
homologs line up along the equator
anaphase I
spindle fibers move homologous chromosomes to opposite sides
telophase I
Cytoplasm divides, 2 daughter cells are formed
prophase I
homologous chromosomes pair up & form tetrad; crossing-over occurs
telophase II
nuclear membrane forms, cytoplasm divides, 4 daughter cells
metaphase II
chromosomes line up along the equator, not in homologous pairs
prophase II
The duplicated chromosomes and spindle fibers reappear in each new cell.
anaphase II
chromatids separate
What does DNA stand for?
deoxyribonucleic acid
what is your complete set of genetic information called?
genome
What field in genetics considers many genes at a time?
heredity
what are the variants of a gene called?
mutations
how many chromosomes do humans have in each cell?
46 (23 pairs)
22 pairs of human chromosomes are called…
autosomes
what are charts that depict human chromosomes?
karyotypes
Genotype
genetic makeup of an organism
Phenotype
An organism's physical appearance, or visible traits.
the alleles in a population make up…?
the gene pool
what do you call genes that code for proteins?
DNA & RNA
what is a field of study which addresses many of the personal issues that arise in medical technology?
bioethics
the use of organisms with new technologies to produce goods & services is called…?
biotechnology
cells can be divided into 3 main domains - what are they?
archaea, eukarya, bacteria
4 broad categories of cells & tissues in humans
epithelial, connective, muscle, & nervous
Epithelial
pertaining to skin cells
connective
supports body organs
muscle
movement
nervous
carries electrical messages back and forth between the brain and every other part of the body.
4 main organic compound groups
proteins, lipids, carbohydrates, & nucleic acids
Proteins
Nutrients the body uses to build and maintain its cells and tissues
Lipids
fats and oils
Carbohydrates
starches and sugars
nucleic acids
DNA and RNA
another term for cell membranes
plasma membrane
are somatic cells haploid or diploid?
diploid
which cell part is composed of a phospholipid layer?
the cell membrane
What is programmed cell death?
apoptosis
3 major phases of the cell cycle
interphase, mitosis, cytokinesis
G1 (interphase)
Cell growth
S (interphase)
DNA replication
G2 of interphase
the shortest phase (organelles and molecules required for cell division are produced)
phases of mitosis in order
prophase, metaphase, anaphase, telophase
what is on the tips of chromosomes that tell them to divide?
telomeres
2 broad types of interactions among cells
gap junctions & tight junctions
gap junctions
provide cytoplasmic channels between adjacent animal cells
tight junctions
Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
what type of stem cells give rise to every cell type?
embryonic stem cells
how are iPS (induced pluripotent stem cells) produced?
what are the main reproductive organs in males?
penis, scrotum, & testicles
another term for sex cells
gametes
which gland in the male reproductive system secretes fructose?
seminal vesicle
which phase of meiosis is termed the reduction division?
meiosis I
which phase of meiosis is termed the equational division?
Meiosis II
the process of the formation of sperm cells in males
spermatogenesis
in females, during meiosis I, the primary oocyte divides into 2 cells. What are they called?
after puberty, meiosis I in females continues but HALTS at what phase?
what order in which a morula, blastocyst, & blastomere developed
blastomere, morula, blastocyst
3 primary germ layers
ectoderm, mesoderm, endoderm
How do conjoined twins form?
fertilized egg separates as in identical twins, but not completely
What is a critical period?
The first trimester is the critical period of organogenesis, when the major organs form. Exposure during this time, and particularly during the first 2 months—the embryonic period—can result in dysmorphia.
what do we call the most sever rapid aging disorders?
progeria
Explain the process of oogenesis
Oogonium undergoes mitosis to produce a primary oocyte, which undergoes meiosis to produce a secondary oocyte and a polar body. The secondary oocyte produces a polar body and a mature ovum
When do men and women begin meiosis?
Men: at puberty, continues throughout life Women: a fetus, only completes if oocyte is fertilized by egg
What phases are oocytes in during different stages of life?
-Birth: all oocytes are in prophase I-After puberty: meiosis occurs in one or several oocytes each month but ends at metaphase II-If fertilized in fallopian tube, then meiosis completes
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