Science 9 - Biology Unit Test Flashcards
infertility
inability of couple to have baby; might be because…
- male not producing enough sperm
- male producing deformed/defective sperm
- female unable to release eggs (not enough of right kind of hormones)
- medical procedures (chemotherapy or radiation therapy)
cri-du-chat syndrome
also known as crying cat syndrome
- 1 in 50 000 individuals
- caused by deletion on short arm of chromosome 5
- usually small at birth
- respiratory problems
- larynx (voice box) doesn’t develop correctly (causes cat-like cry)
- small head, small chin
- unusually round face, widely set eyes
fetal development
- three layers of gastrula form tissue & organs of a baby
- takes 38 weeks & divided into three trimesters (three months long)
- at end of 8 weeks, embryo called fetus
blastula
- end of second week
- embryo 1.5mm in diameter and has hollow ball of cells
- cells now embryonic stem cells
Turner syndrome
- 1 in 5000 females
- only 1 ‘x’ chromosome instead of 2
- female sexual characteristics underdeveloped
- short stature
- swelling of hands and feet
- low hairline, low-set ears
- reproductive sterility, absence of menstrual period
- increased weight –> obesity
homologous chromosomes
a pair of matching chromosomes (one from each parent)
when do chromosome mutations occur?
during meiosis
when is oocyte cryopreservation used?
- women diagnosed with cancer who have not begun chemotherapy or radiation therapy
- women undergoing assisted reproductive technologies who do not consider embryo-freezing an option
- women who want to preserve future ability to have children, because they do not yet have a partner, or for other personal or medical reasons
mating
process by which both gametes (sex cells) arrive at the same place at the same time
haploid number
(n)
one set
pair of chromosomes
what do karyotypes show?
when whole chromosome mutations have occurred
- can be analyzed to diagnose and treat patients with genetic disorders or syndromes
result of whole chromosome mutations in meiosis 1 & 2
1 gamete will have 2 copies of 1 chromosome, and another will have none
ectoderm
- outer layer
- cells form skin and nervous system
embryonic development
- early development of organisms
- takes place in humans during first 2 months (8 weeks) after fertilization
impact reproductive technologies in society
- IVF causes higher chance of birth defect
- most unused embryos donated to stem cell research
- with AI, most children never know who biological father is
- in surrogacy, sometimes arguments over custody of child
hormone therapy
might cause female to ovulate
third trimester
continued growth
- rapid weigh gain; growth and accumulation of fat (26-38 weeks) {40-50 weeks}
three layers of cells that organize during gastrula
- ectoderm
- mesoderm
- endoderm
which has a greater impact; chromosome or gene mutations
chromosomes mutations because bigger DNA sequences are changed
independent assortment (during meiosis 1)
- homologous pairs of chromosomes separate at equator, move towards opposite poles of the cell
- many different possibilities for how they will separate produces variation –> there are over 8 million sperm combinations possible for the 23 pairs in an egg or sperm cell!
females (gamete formation)
meiosis 1 - produces 2 egg cells (cytoplasm & organelles are not equally divided)
meiosis 2 - produces 4 cells —> three smallest disintegrate –> one large haploid egg cell
result of meiosis? (gametes)
four haploid cells, each with half the number of chromosomes
advantages of external fertilization
- little energy required
- large number offspring produced at once
- offspring far from parents (less competition and genetic variation maintained)
crossing over during meiosis 1
- parts of non-sister chromatids “cross over” each other and exchange segments of DNA
- this produces genetic variation
gene mutation
change in specific order of A, G, C, and T bases that make up a particular gene
difference between meiosis 1 and 2?
meiosis 1:
- homologous chromosomes line up at the equator, then separate and move to opposite poles of the cell
meiosis 2:
- chromatids of each chromosome are pulled to opposite poles
Down syndrome
- 1 in 1000 individuals
- extra 21st (trisomy 21)
- mild to moderate learning disabilities
- almond shape to the eyes
- shorter limbs, pore muscle tone
- larger than normal space between big and 2nd toe
- protruding tongue
what happens during fertilization?
2 gametes (n) fuse to form a zygote (2n)
in vitro fertilization
- used when female Fallopian tubes are blocked (tube connects ovaries to uterus)
- egg cells removed from ovaries and placed in Petri dish, fertilized eggs implanted into uterus few days after fertilization
- more than one egg used, multiple births common
surrogacy
couple asks surrogate mother to carry embryo provided by couple, sometimes surrogate mother asked to produce egg
intracytoplasmic sperm injection
- only one sperm cell in egg cell, zygote later inserted in female’s uterus
- only 25% of ICSI procedures result in birth
advantages internal fertilization
- embryo protected (inside female) & parents care for young –> more offspring survive
mesoderm
- middle layer
- cells form kidneys, muscles, blood vessels, reproductive organs, bones
where does the genetic information in the zygote come from?
half from one parent, half from the other
n + n = 2n
artificial insemination
- sperm collected and injected into female
- widely used to breed farm animals
- in humans, sometimes sperm collected from female’s partner and injected into female. sometimes, if male unable to produce enough viable sperm, sperm donor (usually anonymous) is used
how DNA can be affected
- lost
- duplicated
- inverted (flipped)
- moved within a chromosome
- moved to another chromosome
how can pollen be transported?
- colourful flowers attract pollinators which spread pollen as they take nectar from flowers
- by the wind
- for plants without flowers: pollen transported by wind from male cones to female cones
pollination
- form of internal fertilization used by plants
- transfer of male gametes in pollen from male reproductive part to female reproductive part
- pollen tube forms to deliver sperm cells to egg cells once pollen lands on female part of plant (pistil)
- after fertilization zygote grows into embryo, nourished by food within seed in which it grows (seed protects embryo)
assisted reproductive corrective technology procedures
- hormone therapy
- artificial insemination (AI)
- in vitro fertilization (IVF) {test tube baby}
- gametes intrafallopian transfer (GIFT)
- intracytoplasmic sperm injection (ICSI)
- oocyte cryopreservation
gametes
specialized cells necessary for reproduction
ex; eggs, sperm, pollen
why don’t large chromosome mutations usually pass down to new generations?
offspring doesn’t develop, doesn’t succeed, doesn’t reach reproductive age, or is infertile
first trimester
developing organ systems
- brain, spinal cord forming (3 weeks) {4 mm}
- digits, ears, organs, and muscles forming (6 weeks) {4 cm}
- sexual differentiation (9 weeks) {9 cm}
what does sexual reproduction require?
two parents
what does haploid vs. diploid refer to?
the number of chromosomes
second trimester
growth
- fetal movements felt (16-18 weeks) {20 cm}
- eyelids open, fetus can survive with special care if born now (24 weeks) {35 cm}
males (gamete formation)
meiosis 1 - produces 2 cells
meiosis 2 - produces 4 cells with cytoplasm & organelles equally divided (4 haploid sperm cells
how are chromosome mutations caused?
by mutagens
endoderm
- inner layer
- cells form lungs, lining of digestive system
stages of sexual reproduction
- mating (ritual)
- fertilization (external or internal)
- development
morula
- end of first week
- embryo is 0.2mm in diameter
who are offspring genetically different from?
in sexual reproduction
- each other
- either parent
- any other member of their species
what is meiosis?
the process that produces gametes with half the number of chromosomes as body cells
external fertilization
- occurs outside bodies of parents
- gametes released by parents = fertilization happens when sperm and egg cell come in contact
- common in underwater animals and animals who live in moist environments (water needed for male gamete to travel to female gamete)
disadvantages internal fertlization
- requires more energy to find mate
- produces fewer zygote
fertilization
process when an egg cell is penetrated by a sperm cell and the haploid genetic information of both male and female gametes combine
gamete formation
different in males and females
once the egg is fertilized, when will cell division occur?
- there are enough nutrients for rapidly dividing embryo
- temperature warm enough for proteins and enzymes to function properly during chemical reactions in developing embryo
- enough moisture so embryo doesn’t dry out
- embryo protected from threats (predators and environment)
internal fertilization
- sperm cells deposited inside female body (where they meet egg cell)
- one sperm penetrating egg cell results in membrane changing electrical charge that prevent more sperm from entering egg –> only one set of male chromosomes can unite with the chromosomes in the nucleus of the egg cell
gametes intrafallopian transfer
egg cells removed from ovaries & placed in mixture of sperm, mixture placed in Fallopian tubes so fertilization can take place in woman’s body
oocyte cryopreservation
- woman’s eggs (oocytes) extracted, frozen and stored
- when she is ready to become pregnant, eggs thawed, fertilized, and transferred to uterus as embryos
what does the zygote undergo to become an embryo?
mitosis and cell division
diploid number
(2n)
two sets of chromosomes
Klinefelter syndrome
- 1 in 500 males
- male with an extra ‘x’ chromosome (XXY)
- small testicles –> reduced fertility
when do whole chromosome mutations occur in meiosis 1?
if homologous chromosomes do not seperate
disadvantages external fertilization
- many gametes don’t survive outside of parent’s (usually female) body
- zygotes and embryos not protected
- parents don’t care for offspring –> few survive
karyotypes
pictures of an organism’s chromosomes arranged in homologous pairs
stages embryonic development
- Morula
- Blastula
- Gastrula
genetic diversity
inherited genetic differences (variation) in a species that give many organisms a survival advantage
when do whole chromosome mutations occur in meiosis 2?
if sister chromatids do not seperate
telophase
- spindle fibres disappear
- nuclear membrane forms around each separated set of chromosomes
- nucleolus appears
how does asexual reproduction occur?
occurs without gametes (sex cells) coming together
enzyme in stem cells?
enzyme telomerase
why do cells divide?
- cells receive nutrients & removes waste through cell membrane
- size of cell membrane determines how much can enter/leave the cell
- cells grow –> volume increases more quickly than surface area
- once cell is certain size, membrane can’t support contents anymore
- cells must divide to reach favourable surface/volume ration
- when they get too big they divide
reproductive cloning (adult DNA cloning)
- produces a genetic duplicate of an organism
- takes a nucleus from a cell (from the organism to be cloned) and puts it into an egg cell that has had the nucleus removed
problems of reproductive cloning (adult DNA cloning)
- only about 10% of clones survive
- clone can be abnormally large/sized
- clones have higher rates of cancer and infection
- clones age faster than others
do cancer cells function as parts of your body?
no, cancer cells are not specialized, they do not make proteins for organ cells.
late prophase
- nuclear membrane disappears
- spindle fibres finish forming and attach to centromeres or chromosomes
what does telomerase do?
stop chromosomes from tangling/fraying with other chromosomes
how does vegetative reproduction work?
grasses, lilacs, and many forms send out rhizomes (underground stems.)
some woody shrubs reproduce asexually by using their ordinary stems, branches of these plants take root wherever they touch the ground.
ex: currants, willows, and forsythias
some plants send out runners which are special stems (they have a small, new, genetically identical plant on them.) when new plant touches ground; it roots, forming a whole new plant.
ex: strawberries and spider plants
early prophase
- nucleolus disappears
- spindle fibres begin to form
what is cancer?
certain diseases that result from uncontrolled cell division
anaphase
- spindle fibres pull sister chromatids to opposite poles of cell
stomach lining cells are replaced every:
2 days
disadvantages of vegetative reproduction
- clones, or new plants, grow close to the parents (compete for same resource)
- clones, or new plants are genetically identical. illness or disease could kill all of them
why do cancer cells release chemicals to attract blood vessels?
blood vessels branch into tumour and deliver nutrients to it
how can asexual reproduction be characterized?
a. only one parent is required
b. no gametes (sex cells) required
c. offspring are clones (same set of chromosomes)
d. no specialized reproductive cells or structures
Five major types of asexual reproduction used by organisms:
- binary fission (bacteria)
- budding
- fragmentation
- vegetative reproduction
- spore formation
mitosis
divides the duplicated contents of the nucleus into two equal parts
what does therapeutic cloning require?
stem cells
- cells that have not specialized yet –> have the potential to become different types of cells
- can use adult stem cells or embryonic stem cells
how do cancer cells escape programmed cell death? what does this mean for their chromosomes at cells division?
90 percent of human cancer cells don’t turn off telomerase gene. telomere caps of chromosomes do not shorten during cell division (divide longer than regular cells.)
which are more desirable to use in therapeutic cloning? adult stem cells or embryonic stem cells? why?
embryonic are more desirable because they can be more types of cells
benefits to humans of vegetative reproduction
- food source (e.g. potatoes)
- increase yield & speed of harvest
- produce crops with specific qualities:
- taste/texture
- storage/handling
- form single-celled spores (specialized reproductive cells)
- have a nucleus, cytoplasm, and protective covering
- covering protects spore from physical damage/drying out
- carried away from parent by wind/water. when spore lands in favourable environment, it develops into a new organism through mitosis.
how is therapeutic cloning used?
to correct health problems
how many times can a human cell divide?
50 times
skin cells are replaced every:
20 days
three parts/phases of interphase
- growth and preparation
- DNA replication
- growth and preparation continued
in cytokinesis: the 2 nuclei are separated into ________________ that are ____________ the original cell.
2 daughter cells, identical to
grafting
- does not happen naturally. humans must make this happen.
- stems called sions are attached to the rooted stock of another species (quicker harvest)
what are the 3 stages of the cell cycle?
interphase
mitosis
cytokinesis
what monitors cell activity. why?
special proteins at the checkpoints monitor the cell activity and send this information to the nucleus.
fragmentation
pieces of parent’s body breaks off. some fragments produce clones. sometimes occurs by accident. more often, it is deliberate.
ex: sea stars and flatworms reproduce by fragmentation
how do cancer cells spread?
tumour cells break away and are carried by blood vessels to new location where they divide and form new tumour
how can stem cells be used?
to replace damaged cells in patients with diabetes, spinal injuries, or Parkinson’s disease
budding
offspring starts as growth/bud on the body of the parent as a result of repeated mitosis and cell divisions
difference healthy cells cancer cells
healthy cells: grow in single layer, stop dividing when they stop receiving messages from nearby cells
cancer cells: don’t respond to messages, begin to grow in multiple layers
define vegetative reproduction
only occurs in plants. form new plants without making seeds (without sexual reproduction)
stages of interphase
- growth and preparation
- DNA replication
- continued growth and preparation
when are activities within the cell monitored/controlled?
at specific stages/checkpoints
what cause mutations?
mutagens (viruses, x rays, ultraviolet light, and chemicals such as acetone in cigarettes.
phases of mitosis
early prophase late prophase metaphase anaphase telophase
brain cells are replaced every:
30-50 years
binary fission
organism splits in two roughly equal halves, pinches off (cytokinesis) to form two new organisms. mitosis not necessary because no nucleus in bacteria. single dna just replicates.
what happens when a cell is exposed to radiation during mitosis?
chromosomes fail to move to opposite poles of a cell during anaphase
What is cloning?
cloning is the process of making a genetically identical organism through nonsexual means
what happens before mitosis?
DNA molecules that replicated during interphase join to form sister chromatids of a chromosome joined by a centromere
cytokinesis in animal cells
the cell membrane pinches together
metaphase
- spindle fibres pull chromosomes into line at equator
interphase
- cell increases in size, makes protein (carries out the functions necessary for survival)
- cells copy/replicate itself and 3 billion base pairs of DNA information. DNA ladder break apart, new bases pair with bases on original DNA
- cells make proteins for new daughter cells formed after cytokinesis. chromatin (containing replicated DNA) is loosely coiled. dna copied into rna. organelles duplicated. two new identical dna molecules produced
what if a mutation occurred in a gene producing instructions for a checkpoint protein?
cell cycle control will be lost. damaged cells may divide uncontrollably.
what treatment are cancer researchers looking for?
drugs that work by blocking cel division in a cancer cell and preventing formation of tumours
uses of human assisted cloning?
- to save genetic information from endangered species
- to mass-produce an organism with a desirable trait
- (for example pine trees that are resistant to pine beetles)
what are embryonic cells? how long can they live for?
early stage cells of developing embryo. indefinitely.
what happens to nuclei of cancer cells? why?
become large and abnormal because cell division no longer functions and chromosomes do not divide correctly.
when/why do embryonic stem cells lose their “fountain of youth?”
once a cell becomes specialized
cytokinesis in plant cells
a cell plate forms
what does asexual reproduction mean?
without sex
clone
identical genetic copy of its parent
cytokinesis
separates the two nuclei and cell contents into two daughter cells
when will cells not divide?
- not enough nutrients to support cell growth
- dna in nucleus not replicated
- dna damaged
ex; chromosomes not attached to spindle fibres in metaphase, chromosomes not moved to poles in anaphase
