Genetics
What is genetics?
the study of heredity and the study of varietion
what does DNA stand for?
Deoxyribonucleic acid
what is DNA?
Contains the generic instructions for development and reproduction
What is the structure of a DNA strand
double helix
what is the backbone of DNA made out of
Phosphate and deoxyribose sugar molecules
What are ladder rungs made out of
Nitrogenous bases
what makes up a nucleotide
phosphate, sugar, base
what are the 4 different types of DNA bases
adenine, thymine, guanine, cytosine
what do bases contain?
nitrogen
what bases pair together?
AT, GC
what are adenine and guanine?
purines
what are thymine snd cytosine?
pyrimidines
is the order of base pairs different for everyone?
yes
why do cells divide?
growth, repair, reproduction
what are the three stages of cell cycle?
interphase, mitosis, cytokinesis
what is the longest phase?
interphase
what are the three phases of interphase?
gap phase, synthesis, gap phase 2
what is the process of mitosis?
division of the nucleus
what are the four stages of mitosis
PMAT
what is cytokinesis
division of the cytoplasm
what is a gene?
a gene is a segment of DNA that codes for a particular trait
what are chromosomes?
composed of DNA and proteins
what happens in prophase?
chromatins condese to form paired chromosomes
centrioles move to each pole
nuclear membrane breaks down
what happens in metaphase
spindle fibres attach to centromeres
chromosomes line up at metaphase plate
what happens in anaphase
spindle fibres shorten
sidter chromstids seperste snd move to opposite poles
what happens in telophase and cytokinesis
nuclear envelope forms around each group of daughter chromosomes
cytoplasm splits in half (cytokinesis)
cells return to interphase
plants vs animals
cell membrane pinches near the middle of the cell dividing cytoplasm into two new cells.
what is a clevage furrow?
the cell membrane pinches near the middle
what happens in plant cells?
a cell plate develops across the centre of the cell forminf a new cell wall between the teo nrw cells
what is rhe main purpose of meiosis I
to create gametes for sexual production, cut chromosomes in half
why does crossing over exist?
to create a greater genetic diversity
what happens to the non-sister chromatids during Prophase I
they come together to form a tetrad snd cross over
how many chromatids in each cell in human cells after prophase I
92 chromatids
do the homologous pairs or the sister chromatids line up in the middle of the cell during metaphase I
the homologous pairs line up in the middle
how do the homologus pairs line up in metaphase I(whats rhe arrangment called)
independant/random assortment
what happens in anaphase I
homologus chromosomes seperate whd move to opposite poles of the cell
what happens in telophase I
the nuclear membrane begins to form around each nucleus
how many chromatids in each human cell in telophase I
46 chromatids
in meiosis, how do parent and daughter cells compare?
2 different cells and chromatids are half
is thwre duplicstion during interphase I or II
Interphase I
what is the purpose of meoisis II
23 chromosomes in each cell (haploid) 4 generically unique haploid cells
what happens in prophase II
nuclear membrane dissolves
spindle fibres form centrioles move to opp ends
how does the chromatid arrangment stage look different from metaphse I to metaphase II
the chromosomes line up in the center of the cell at the equatorial plate. the chromosomes are sister chromatids still connected by their centromere.
what happens to the sister chromatids in eavh cell in anaphase I
split at centromere both the sister chromatids
move to opposite ends of the poles
what process does Anaphase II look like and how is it different
the chromosomes are generically unique due to crossing over that occured in prophase I
in telophase II, how many cells are there
4
how many chromatids are in each cell in telophase II
23
at the end of meiotic cell division how are the dsughter cells the same
all have 23 chromatids and are haploid but they are generically different
at the end of meiotic cell division how are the parent cells the same
the original cells had 46 chromosomes (diploid) but are generically unique
how do mitosis snd meiosis parent cells differentiate
mitosis is symatic, meiosis is spermatocyte and oocyte
how do mitosis and meiosis daugjter cells differentiate
mitosis is 1 symatic, meiosis is 4 sperm cells and female is 1 egg cell 3 polar bodies
mitosis and meiosis chromatid # before division process
92 for all
mitosis snd meiosis # of chromatids in dsugjyer cells after division process in complete
46 in mitosis, 23 in meiosis
mitosis and meiosis, which daughter cells are haploid and diploid
mitosis is dioloid, meiosis is haploid
meiosis snd mitosis, # cells when division is done
2 in mitosis, 4 in meiosis
meiosis and mitosis # divisions and # of phases
mitosis = 1 division, 4 phases, meiosis = 2 divisions, 8 phases
what is the generic makeup of mitosis and meiosis cells when done (are rhey identitcal or unique)
mitosis = identical, meiosis = unique
what are the mutation errors that csn occut in mitosis
deletion, duplicate, inversion, translocation
what are the mutation errors that csn occut in meiosis
deletion
duplication
inversion
translocstion
nondisjunction
what mutation is this? ABC-DEF --> AC-DEF
deletion
what mutation is this ABC-DEF --> ABBC-DEF
duplication
what mutation is this ABC-DEF --> AED-CBF
inversion
what mutation is this ABC-DEF GH-IJKL
ABC-JKL
GH-IDEF
what is a zygote?
a fertilized egg
what are common mutagens?
x-rat, radiation, chemicals, viruses
do mutations happen in mitosis and meiosis
yes
all mutations result in altered chromosomes but the number of chromosomes is still correct
.
if meiosis happens properly how many chromosomes should be in each egg and sperm?
23
what is nondisjunction?
when chromosome pairs (Meiosis I) or sister chromatids (meiosis II) fail to seperate
what is monosomy and what is caused by
missinf a chromosome, nondisjunction
what is trisomy and what is caused by
an extra chromosomes, nondisjunction
when a zygote is missinf 1 chromosome out of a homologus pair it usuallt results in what
non-viable embryo and a miscarraige
what is turners syndrome?
only affects women and is a missinf part of the X chromosome
what is a partial monosomy?
when an arm does not properlt reattsch durinf crossover (cri du chat)
are trisomy or monosomy
more likely to be viable?
trisomy
what chromosome is extra when you have down syndrome?
21
what extrw chromosome di tou have if tou have edwards syndrome
18
where do tou find somatic cells and are rhey diploid or haploid?
in the body and rhey are diploid cells
where do tou find gamete cells and are they diploid or haploid?
the sex cells and are haploid cells
what would happen if meiosis didnt occur?
the chromosome number in each generation would double and the offspring would die
how is a chromosome made up
two identical sister chromatids attacthed at their centromeres
do centriole pairs relplicate in interphase 1
yes
which phase in meiosis is the longest and most conplicated?
prophase I
what is synapis?
chromosomes come together in homologus pairs
what is the shortest phase in meiosis?
metaphase I
whats a trait?
a chatacterisrc passwd down feom gwnerations
whats an allele?
an allele is a type of trait eg. blue eyes from eye colour
what are genes
the things that carry your informstion rnat decides if tou get a certain trsit
whats a gamete
a repdoructive cell
whats a somatic cell
a cell in the body
how many chromsome pairs do humans have?
23
what extra chrimosome do you have if you have patau syndrome
13
what are two reasons why siblings look different
because if crossing iver and random assortment