bio_20240103035114(AutoRecovered) Flashcards
1
Q
what is the outmermost layer of your skin composed of
A
dead epithelial cells
2
Q
what is the outer layer of skin
A
epidermis
3
Q
what is the inner layer of skim
A
dermis
4
Q
what does the dermis do
A
the cells present in the dermis are responsible for reproducing in order to replace any lost or dead skin cells.
5
Q
4 differences between sexual and asexual reproduction
A
- a: 1 parent involved s: 2 parents involved-a: results in offspring that are genetically identical to both the parent and other offspring s: results in offspring that are genetically different to both their parents and other offspring-a: involved mitosis s: involves meiosis-a: happens most frequently in unicellular organisms s: happens most frequently in multicellular organisms
6
Q
how and why are sexually and asexually offspring different
A
asexual reproduction results in offspring that are genetically identical to the parent and other offspring, as all genetic material is received from. a single parent that duplicates its own DNA. sexual reproduction however, results in offspring that are genetically different to the parents as well as otehr offspring, this is because genetic material is received from both parents.
7
Q
relate cell reproduction to replacing skin cells
A
underneath the layer of dead skin is a layer of epithelial cells called the epidermis- the outer layer of the skin, and underneath the epidermis lies a layer of cells responsible for the constant reproduction of new skin cells via mitosis. these new cells will travel through the dermis and replace lost/damaged/deas cells
8
Q
how is cell division involved in growth
A
cell division produces new cells, enabling an organism to increase in size
9
Q
chromatin
A
NAME?
10
Q
chromosomes
A
NAME?
11
Q
centromere
A
region in which two sister chromatids are joined tightly together
12
Q
sister chromatids
A
two identical joined copies of the same chromosome
13
Q
prokaryote
A
type of cell that does not have a nucleus or any membrane-bound organelles
14
Q
Eukaryote
A
type of cell that has a nucleus and membrane-bound organelles
15
Q
cell cycle
A
the sequence of events eukaryotic cells that divide go through from birth as a result of cell reproduction to the time the cell itself reproduces
16
Q
interphase
A
stage of the cell cycle in which a cell synthesizes its DNA, synthesizes proteins, grows in size, and increases its number of organelles. 90% of the cell cycle is spent during interphase
17
Q
how does the structure of DNA vary during the cell cycle?
A
genetic material is found in the form of chromatin fibers everwhere during the cell cycle except for at the beginning of the mitotic phase, when they start to condense into chromomomes.
18
Q
mitotic phase
A
the stage of the cell cycle in which the cell is actually dividing. includes 2 processes: mitosis and cytokinesis
19
Q
stages of the cell cycle
A
birth of 2 identical daughter cells by cell reproduction -> G1 cell grows -> S duplication of genetic material -> G2 cell prepares to divide -> mitotic phase cell actually divides
20
Q
mitosis(miotic phase)
A
process of the mitotic phase in which the nucleus and duplicated chromosomes divide and are evenly distributed forming 2 daughter nuclei
21
Q
cytokinesis
A
process of the mitotic phase in which the cytoplasm divides in two. usually occurs before mitosis is completed
22
Q
stages of mitosis
A
4 stages of mitosis :i) prophaseii) metaphaseiii) anaphaseiv) telophase
23
Q
mitotic spindle
A
an apparatus of microtubules that controls chromosome movement during mitosis
24
Q
centrosome
A
microtubule organizing centers in which the assembly of spindle microtubules begins/region in which spindle microtubules are produced
25
centriole
two cylindrical structures located perpendicularly to one another within the centrosomes of animal cells (most plant cells do not have them and their role is not yet clear)
26
occurrences in G2
#NAME?
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occurrences in prophase
#NAME?
28
zygote
fertilized egg cellresulting cells of fertilization
29
fertilization
the union of 2 sex cells (EGG AND SPERM CELL)
30
metaphase
-"meta" as in middle-chromosomes gather on a plane in the middle of the cell-the mitotic spindle is fully formed-all chromosomes are attached to the spindle microtubules with their centromeres lined up halfway between the 2 poles of the spindle
31
anaphase
-sister chromatids separate into 2 daughter chromosomes -daughter chromosomes move along the spindle microtubules to opposite poles thanks to the proteins found in the centromere-spindle microtubules already attached to daughter chromosomes shorten in order to bring them closer to the poles-microtubules not yet attached to daughter chromosomes grow longer, pushing the poles further apart
32
telophase
#NAME?
33
cytokinesis in animal cells
involves a ring of microfilaments creating an indentation down the middle of the parent cell, this ring of microfilaments will contract like a drawstring, deepening the indentation until eventually, the parent cell splits in two resulting in two new daughter cells
34
cytokinesis in plants
involved a a disk of cell wall material called the cell plate forming inside the cell and growing outwards until it reachest the edges of the parent cell wall, dividing the cell in two as it itself becomes part of the cell wall, resulting in 2 daughter cells bound by their own continuous membranes and walls.
35
Meiosis
type of cell division involved in the production of 4 haploid gametes/sex cells
36
karyotype
a display of the 46 chromosmes of an individual
37
homologous chromosomes
two individual chromosomes that have the same genes in the same order, shape, and size but are inherited from different parents and may code for different variations of the same gene
38
are X and Y hiomologous chromosomes?
no, only small parts of the x and y chhromosmes are homologous, making them parttly homolgous. The X chromsome is much larger than the Y chromsomes which leads to most of the genes present in the X chromsomes not having counterparts on the tiny Y, and Y having genes that X lacks.
39
differences between meiosis and mitosis
1) results in 2 daughter cells // results in 4 daughter cells2) results in diploid cells // results in haploid cells3) produces genetically identical daughter cells // produces daughter cells with genetic variation due to genetic recombination4) number of chromsomes stays constants i.e number of chromsomes in parent cell and daughetr cells is the same// number of chromsomes halves5) no crossing over: crossing over6) 1 cell division// 2 cell divisions
40
differences between sister chromatids and homologous chromosomes
homologous chromosomes are 2 individual chromosomes, each derived from a different parent. they have the same shape and size and contain the same genes in the same order however may contain different versions of the same genes. Sister chromatids, on the other hand, when formed, are genetically identical because of the nature of how they are formed, carrying the same version of all their genes.
41
results of meiosis 2
4 haploid daughter cells, each with 23 full-fledged chromosomes
42
results of meiosis 1
2 haploid daughter cells, each with 23 duplicated chromosomes,. i.e sister chromatids still attached
43
prophase 1
#NAME?
44
metaphase 1
#NAME?
45
anaphase 1
#NAME?
46
telophase 1
-chromosomes arrive at the poles on either side of the dividing parent cell- each pole has a haploid daughter nucleus, each consisting of 23 duplicated chromosomes-cytokinesis usually occurs alongside telophase 1, splitting the cytoplasm to produce 2 haploid daughter cells
47
metaphase 2
-chromosomes gather on a plane in the middle of the cell-the mitotic spindle is fully formed-all chromosomes are attached to the spindle microtubules with their centromeres lined up halfway between the 2 poles of the spindle
48
prophase 2
#NAME?
49
anaphase 2
-sister chromatids separate into 2 daughter chromosomes -daughter chromosomes move along the spindle microtubules to opposite poles thanks to the proteins found in the centromere-spindle microtubules already attached to daughter chromosomes shorten in order to bring them closer to the poles-microtubules not yet attached to daughter chromosomes grow longer, pushing the poles further apart
50
telophase 2
#NAME?
51
how does meiosis 1 reduce the number of chromosomes in the daughter cells?
homologous chromosomes separate from one another into 2 daughter cells. since each cell only received 1 of each pair, the number of sets of chromosomes is reduced from 2 in the parent cell to 1 in each daughter cell
52
diploid
a cell that contaisn 2 sets of homologous chromosomes. in humans, a diploid cell would have 46 chromosomes, or 2n, 2 sets of 23 chromosmes
53
haploid
a cell that contains only 1 set of chromosomes. in humans, a haploid cell would have 23 chromosmes, or just n, 1 set of 23 chromsomes.
54
3 events that happen during meiosis 1 but not mitosis
1) unlike in mitosis, in prophase 1 of meiosis 1, duplicated homologous chromosomes attach to form tetrads along their lengths with help of proteis and non-sister chromatids cross over their genetic material2) during metaphse 1, the tetrads are aligned in the centre of the cells, wheread in metapahse of mitosis, idnidviausl duplicated chromsomes line up in a single-file formation along the metaphase plate3) in anapahse 1, the isster chromatids fo not seperate from their partners like in anaphse of mitosis, rather, it is the pairs of homologous duoliacted chromsomes that are sperated from one another
55
name & explain the 2 events that contribute ti genetic variation in sexually reproducing organisms
1) the assortment of chromosomes that end up in the resulting cell is completely random, which increases the chance of offspring having diffrent assortments of genes, resulting in genetic variatopm2) teh exhange of genetic materials
56
crossing over
occurs after tetrads are formed, during prophase 1the exchange of genetic material between homologous chromosomes when crossing over begins, homologous chromosomes are closely paired all along their length. There is a precise gene-by-gene alignment between adjacent chromatids of the two chromosomes and segments of the two chromatids can be exchanged at one or more sites
57
trait
a variation of a particular chracter
58
pattern of inheritance
the way characteristics are transferred from parents to offspring
59
blending hypothesis of inheritance
stated that genetic material from parents mixed to create a new trait which would then be inherited by the offpspring
60
disproving the blending hypothesis
the blending hypothesis failed to explain how traits disappear in 1 generation and reappear in later ones
61
genetics
the study of heredity
62
particulate hypothesis of inheritance
parents pass on to their offsprng sepearet and distinct factors (now referred to as genes) that are responsible for inherited traits. these heritable factors retain their identity generation after generation
63
self-fertilisation
sperm from the pollen of a flower fertilising the eggs in the flower of the same plant. when both male and female gametes are produced by the same individuals and result in fertilisation
64
cross-fertilisation
sperm from the pollen of one flower fertilising the eggs in the flower of a different plant
65
true-breeding
when a plant produces off spring identical in appearance to itself generation after generation when self-fertilised. caused by having homozygous alleles
66
how did mendel test the particulate hypothesis and ensure cross fertilisation
to test the particulate hypothesis, mendel crossed true breeding plants that had 2 distinct and contrasting traits-for example, purple or white flowers who would serve as parents for the next generation. he crossed the two by first, cutting of the immature stamens off of one flower to prevent self fertilisation and then dusting the carpel with pollen from another plants nature stamens to cause fertilisation.
67
how did mendel ensure self-fertilisation
to ensure self fertilisation mendel tied a cloth bag around the bushes with the true breeding pea plants' flowers so that pollen from other plants could not enter
68
how does the particulate hypothesis differ form the beldning hypothesis
the blending hypothesis stated that genetic material from parents mixed to create a new trait which would then be inherited by the offspring, however, the particlate hypothesis stated that parents pass on to their offsprng sepearet and distinct factors (now referred to as genes) that are responsible for inherited traits. these heritable factors retain their identity generation after generation, and thus, unlike in the blending hypothesis, do not mix
69
the difference between self fertilisatiion and cross fertilisati
self fertilisation occurs when sperm from the pollen of a flower fertilising the eggs in the flower of the same plant. when both male and female gametes are produced by the same individuals and result in fertilisation, cross fertilisation however occurs when sperm from the pollen of a flower fertilises the eggs in the flower of a different plant
70
hybrid
the offspring of 2 different true breeding varieties
71
monohybrid cross
a pairing in which the parent plants differ in only one character
72
2 alleles for
every genes in an organisms cells
73
punnett square
diagram that shows all possible outcomes of a genetic cross. used to predict probabilities of particular outcomes if the genotypes of both parents are known
74
mendels four hypothesis
1- there are alternate forms of gnees called alleles2- for each inherited character an organism has 2 alleles for the gene controlling that character , one form each parent. if the two allels are the same, the individual is homozygous for that character. if the two alles are different the individual is heterozygous3-when only 1 of the two different alles in a heterozygous individual appears to affect that trait, the allele is called the dominant allele. and in such cases the other allel that does not appear to affect the trait is called the recssive allele4_ the principle of segregagtion: two allels for a character segregate during the formation of gametes so that each gamate carries only 1 allels for each character
75
genptype
the genetic makeup or combinnation of alleles
76
phenttype
the observable or physiological traits of an individual
77
testcross
breeidng an indivual of unknown genotype but dominant phentoype with a homozygous recessive individual. the appearance of the offspring resulting from the testcross will reveal the genotype of the mystery parent because the homozygous recessive parent can only contribute a recessive allele to the offspring,, the phenotype will indicate the llele contributed by the mystery plant. if the mysteryparent is homozygous dominant, all offspring would have the dominant phenotype, but if it is heterozygous the the phenotypic ratio of dominant to recessive would be 1/2:1/2
78
dihybrid crosss
crossing organisms that differ in two chracters
79
principle of independant assortment
during gamate formation in an f2cross, a particular allele for one character can be paured with either allele of another character and are sorted into gamates independently of one another
80
dihybrid F1 cross ration
9:3:3:1
81
intermediate f2 cross ratio
01:02:01
82
intermediate inheritance
for some characters of organisms neitehr allee is dominant the heterozygotes have a phenotype that is intermediate between the phenotypes of the two homozygotes.
83
multiple alleles
for some genes severeal alles exist in the population which expand the variety and number of possible genotypes and phenotypes
84
codominance
a type of inheritance iin which 2 alles of the same gene are expressed saparatel to yield different traits in an individual
85
characteristic of mendelian genetics
#NAME?
86
difference between intermedite inheritance and codominance
unlike in intermediate inheritance, the phenotype is no intermediate but rather shows the separate traits of both alleles
87
law of dominance and uniformity
some alles are variants of a particular gene found at the same chromosmsomal locus are dominant over other alles of a given gene unless both alles are recessive
88
polygenic inhertiance and its effects on the population
when 2 or more genes affect a single characterthe potential combinations of alleles an dthus range in phenotype increases with the number of genes that affect that character
89
what environmental factors affect which human traits
nutrition- heightexercise-buildexposue to sunlight- skin tonealtitude of ones home, physical activity level, presence of infection- blood count
90
phenotypic ratio for dominant recessie f2 cross
03:01
91
what is the likely echanism of inheritance for a character with a large range of phenoypes
polygenic inheritance. polygenic inheritance is when 2 or more genes affect a single character. the potential combinations of alleses (and subsequently the range of phenotypes) for a certain character increases proportionally with an increase in the number of genes that effect it, thus augmenting the range of phenotypes got that character
92
chromosome theory of inheritance
genes are located on chromosomes and the behaviour of chromosomes during meirosis an feritilisation accounts for inheritance patterns. indeed it is chromosomes that unergo segregation and independent assortment during meiosis and thus account for mendels two principes
93
locus
the location of a gene on a chromsomes
94
location of allels
alles of a gene reside at the same gene locus on homologous chromsomes
95
genetic linkage
the tendency for alles on one chromsome to be inherited together
96
what affects genetic linkage
the closer 2 genes are on the same chromosme the greater the genetic linkage. the farther apart the genes are the more likely it is that a crossover events will separate them
97
exceptions to independant assortment and segregation
when genes are loacted on separate chromsomes they sor indepensdantl of each other during meiosis and are sorted into different gamates but when genes are located on the same chromosome and exhibit great genetic linkage (that is, their loci are close together) their allles would not tend to be sorted into gamates independently as they would stay together during meiosis.
98
sex linked gene
any gene that is located ona sex chromosomemost sex linked genes are x-linked as the X chromosome is much larger and contains more genes than the Y chromsome
99
why are sex-linked disorders more prevalent amngst men
sex-linked siroders are more rpevalent amongst the male population s most sex linked disorders are x linked and recessive, meaning that if a male (who would have only 1 x chromosome) were to inherit a single copy of the disorder's allles, it would be expressed as only 1 copy of the recessive alle would be necessary. females on the other hand would need 2 copies of the recessive alle in order to express the disorder which is much less likely to happen in comparison to men as the probability of a single parent having the disorder is greater than both having it and subsseuqnetly passing it on.
