6-Chromosomal Function In Gametes/Gametogenesis And Sex Inheritance/Determination In Animals Flashcards
(74 cards)
1
Q
A tightly coiled segments of DNA. Carriers of genetic material that control biological traits and sex determination
A
CHROMOSOMES
2
Q
Either of a pair of chromosomes that determine whether an individual is male or female
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SEX CHROMOSOMES
3
Q
The sex chromosomes of human beings and other mammals are designated by scientists as?
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X and Y
4
Q
In humans the sex chromosomes consist of one pair of the total of?
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23 pairs of chromosomes
5
Q
A reproductive cell of an animal or plant
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Gametes
6
Q
female gametes are called?
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ova
7
Q
male gametes are called?
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sperm
8
Q
What is the specialized cell division process that produces gametes by reducing the chromosome number from diploid (2n) to haploid (n)?
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Meiosis
9
Q
Homologous chromosomes separate, reducing the chromosome number by half
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Meiosis I
10
Q
Sister chromatids separate, similar to mitosis
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Meiosis II
11
Q
What phase where homologous chromosomes exchange genetic material, increasing variation.
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Crossing over(Prophase I)
12
Q
Chromosomes align randomly, leading to,different genetic combinations
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Independent assortment(Metaphase I)
13
Q
The process of forming gametes (sperm and eggs) for reproduction
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GAMETOGENESIS
14
Q
- production of male gamete or spematozoa that fertilizes the female gamete, ova.
A
SPERMATOGENESIS
15
Q
- shapes and develops the female gametes (ova or eggs)
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OOGENESIS
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Q
- Initial phase of Spermatogenesis
- Consists a series of mitotic division of spermatogonia ending in production of primary spermatocyte
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SPERMATOCYTOGENESIS
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Q
- Creation of spermatids from primary and eventually secondary spermatocytes after they undergo a series of meiosis
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SPERMATIDOGENESIS
18
Q
Differentiation stage of spermatids into mature spermatozoa.
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SPERMIOGENESIS
19
Q
Primordial male germ cells that are the precursors of spermatozoa multiply by mitosis to become spermatocytes throughout adult life
A
SPERMATOGONIUM
20
Q
A cell produced during the second stage of spermatogenesis, formed from spermatogonium by dividing mitotically to produce two diploid primary spermatocytes, then undergoes MEIOSIS I to produce two haploid secondary spermatocytes and dividing spermatids
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SPERMATOCYTES
21
Q
the haploid male sex cell formed after the completion of meiotic divisions, they give rise to the mature spermatozoa after undergoing differentiation.
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SPERMATIDS
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Q
the mature male sex cell capable of fertilizing the ovum characterized by having a compact head and one or more long flagella for swimming
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SPERMATOZOA
23
Q
- Primordial germ cells migrate to the ovaries.
- They undergo repeated mitotic divisions to form numerous oogonia.
- This phase occurs during fetal development and stops before birth
A
MULTIPLICATION PHASE
24
Q
- Oogonia differentiate into primary oocytes.
- They increase in size and accumulate cytoplasmic nutrients.
- Each primary oocyte gets surrounded by granulosa cells, forming a primordial follicle.
- Meiosis I begins but halts at prophase I until puberty
A
GROWTH PHASE
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- At puberty, hormonal signals stimulate some primary oocytes to resume meiosis I.
- Meiosis I completes, forming a secondary oocyte and a smaller first polar body.
- The secondary oocyte begins meiosis II but arrests at metaphase II.
- Ovulation releases the secondary oocyte into the fallopian tube.
- If fertilization occurs, meiosis II completes, producing a mature ovum and a second polar body.
MATURATION PHASE
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- Immature diploid female gamete in the ovary.
- Undergoes mitosis during fetal development, forming primary oocytes.
- Most degenerate before birth; the remaining enter meiosis I and arrest at
- prophase I.
OOGONIUM
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- Formed during embryonic development through oocytogenesis.
- Arrests at prophase I until puberty.
- At puberty, completes meiosis I to form a secondary oocyte
PRIMARY OOCYTE
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- Formed after meiosis I, ready for fertilization.
- Arrests at metaphase II until fertilization occurs.
SECONDARY OOCYTE
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- Haploid cell formed after completion of meiosis II.
- Results when the sperm enters the secondary oocyte, triggering the final meiotic division
OOTID
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- Mature female gamete that fuses with sperm to form a zygote.
- Carries the set of chromosomes contributed by the female
OVUM
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The primary role of these chromosomes is to carry genetic information necessary for the development and traits of a new organism.
Genetic Information Transfer
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During meiosis, homologous chromosomes can exchange genetic material through crossover events, which increases genetic diversity among offspring
Genetic Diversity
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When a sperm fertilizes an ovum, their combined chromosomal sets form a diploid zygote with 46 chromosomes (23 from each parent), ensuring the continuation of species-specific chromosomal numbers.
Fertilization and Zygote Formation
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This process ensures that each new generation inherits the correct number and types of chromosomes necessary for species survival
Species Continuation
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What is the results in the development of individuals with characteristics that allow them to be identified as males, females, or in some cases, hermaphrodites?
Sex determination
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Animals with two different sex chromosomes are of ? and they are thus able to produce two types of gametes.
heterogametic sex
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members of the ? can only produce one type of gamete
homogametic sex
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The mammalian egg was first identified in what year? with fertilization observed later in the century
1827
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The discovery of chromosomal sex determination was made by ? in 1903 while studying mealworms. This finding was crucial in understanding how genetic material influences sex differentiation
Nettie Stevens
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What is the most well-known sex-determination system, especially in humans?
The XX/XY system
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They have two X chromosomes (XX)
Females
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They have one X and one Y chromosome (XY).
males
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What gene on the Y-chromosome triggers male development by initiating testes formation, which produces testosterone and other male-specific hormones?
SRY gene
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What system is a variation of the XY system. In this system, females have two X chromosomes (XX), while males have only one (X0), with "0" indicating the absence of a second sex chromosome. This system is found in insects such as grasshoppers, crickets, and cockroaches
X0 system
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Who proposed the Genetic Balance Theory in 1921 based on studies in Drosophila?
Calvin Bridges
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The theory states that sex is determined by the ratio of X chromosomes to autosomal sets (X:A ratio). A normal diploid fly has two sets of autosomes (2A), meaning the expected X:A ratios are based on this reference
Genetic Balance Theory
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If the X:A ratio is 1.0 (2X:2A), the fly develops as a?
female
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If the X:A ratio is 0.5 (1X:2A), the fly develops as a?
male
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Ratios between 0.5 and 1.0 in X:A ratio produce?
intersex individuals with a mix of male and female traits
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Extreme X:A ratios (≥1.5 or ≤0.33) result in?
metafemales or metamales, which are weak and sterile
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Also called Haplodiploidy is seen in Hymenopteran insects (ants, bees, wasps), sex is determined by whether an egg is fertilized
Sex determination by male haploid
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Unfertilized eggs develop into?
haploid males
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Fertilized eggs develop into?
diploid females
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If a fertilized egg has two identical sex- determining genes, it becomes a?
sterile male
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They can control whether an egg is fertilized by releasing or withholding stored sperm
Females
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What system is the reverse of the XY system—males are ZZ, and females are ZW.
ZW sex-determination system
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What system is found in birds, some reptiles (like snakes and Komodo dragons), and several insect species (such as butterflies and moths).
ZW sex-determination system
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Not all species rely on chromosomes for sex determination. In some reptiles, including turtles and crocodiles, sex is influenced by the incubation temperature of eggs during a critical developmental,period. This phenomenon is known as? where different temperatures result in different sexes.
temperature-dependent sex determination (TSD)
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temperature-dependent sex determination (TSD) in many turtles, cooler incubation temperatures produce?
males
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temperature-dependent sex determination (TSD) in many turtles warmer temperatures produce?
females
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temperature-dependent sex determination (TSD) in crocodiles, moderate temperatures result in?
males
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temperature-dependent sex determination (TSD) in crocodiles both higher and lower temperatures produce?
females
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What pattern in temperature-dependent sex determination (TSD) produces one sex at higher temperatures and the other at lower temperatures?
Pattern I
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What pattern in temperature-dependent sex determination (TSD) occurs when extreme temperatures at both ends of the spectrum produce one sex, while moderate temperatures result in the other?
Pattern II
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In the marine worm(larvae) become male if they contact a female but develop into females if they settle alone?
Bonellia viridis
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In the marine worm Bonellia viridis, larvae become male if they contact a female but develop into females if they settle alone. This is triggered by a chemical called? produced by females
bonellin
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What species like earthworms and some snails, have both male and female reproductive organs?
Hermaphroditic species
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Some fish, reptiles, and insects reproduce through? producing only female offspring without males.
parthenogenesis
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Species like ? can reproduce both sexually and asexually, adapting to mate availability
boa constrictor and Komodo dragon
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Some genes are sex-linked genes, meaning that they are inherited with the sex chromosomes. Genes carried on the X chromosome are called ? and are generally denoted by an X with a superscript gene symbol. These genes are not present on the male Y chromosome
X-linked genes
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Gene Location: Genes are located on the X chromosome.
Occurrence: inheritance present in both females (XX) and males (XY).
X-Linked Inheritance
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What inheritance occurs only in males because females do not have a Y chromosome?
Y-Linked Inheritance
