Unit 5 Flashcards
What is the study of heredity and hereditary variation called?
Genetics
Genetics encompasses the mechanisms and processes that govern the inheritance of traits.
Define heredity.
The transmission of traits from one generation to the next
Heredity explains how characteristics are passed down through generations.
How are traits passed from parent to offspring?
Through genes
Genes are the fundamental units of heredity that carry information for specific traits.
What are segments of DNA that code for basic units of heredity called?
Genes
Genes are responsible for the inheritance of specific traits and characteristics.
How do offspring acquire genes from their parents?
By inheriting chromosomes
Chromosomes are structures that contain genes and are passed from parents to offspring during reproduction.
What type of reproduction involves a single individual?
Asexual reproduction
Asexual reproduction does not require the fusion of gametes.
In asexual reproduction, what is the only source of variation?
Mutations
Offspring are clones, being exact copies of the parent.
How do organisms reproduce asexually?
Through mitosis
Mitosis allows for the generation of clones.
What type of reproduction involves two parents?
Sexual reproduction
Sexual reproduction involves male and female gametes.
What is a key characteristic of offspring produced through sexual reproduction?
Unique combinations of genes
Offspring are genetically varied from both parents and siblings.
True or False: In sexual reproduction, offspring are clones of the parents.
False
Offspring from sexual reproduction are genetically unique.
What are homologous chromosomes?
A pair of chromosomes that carry the same genetic information
They are the same size, length, and have the same centromere position.
How many homologous chromosomes does each individual inherit?
Two homologous chromosomes, one from each parent
One homologous chromosome is inherited from mom and one from dad.
True or False: Homologous chromosomes have different genetic information.
False
Homologous chromosomes carry the same genetic information.
Fill in the blank: Homologous chromosomes are characterized by having the same _______.
genetic information
They also have the same size, length, and centromere position.
What is inherited from the mother in terms of homologous chromosomes?
One homologous chromosome
The other homologous chromosome is inherited from the father.
What is inherited from the father in terms of homologous chromosomes?
One homologous chromosome
The other homologous chromosome is inherited from the mother.
What is the centromere?
Specific area of chromosome where the chromatids attach
The centromere plays a crucial role during cell division.
What is the kinetochore?
The protein complex that assembles at the centromere
The kinetochore is essential for the movement of chromosomes during cell division.
What are spindle fibers?
Structures that help separate chromosomes during cell division
Spindle fibers are formed from microtubules and play a key role in mitosis and meiosis.
Close up image of chromosome
What’s a karyotype of chromosome?
A display of chromosome pairs ordered by size and length
What type of cells are somatic (body) cells?
Autosomes
Somatic cells make up most of the body tissues and organs.
What does diploid (2n) mean?
Two complete sets of each chromosome
What is the diploid number of chromosomes in humans?
2n = 46
This includes all autosomes.
What are gametic cells?
Sex cells
Gametic cells include sperm and eggs.
What does haploid (n) mean?
One set of each chromosome
Haploid cells contain half the number of chromosomes.
What is the haploid number of chromosomes in humans?
n = 23
This is the number of chromosomes in human sperm and eggs.
What are the two types of chromosomes?
Autosomes: chromosomes that don’t determine the sex
Sex Chromosomes: X and Y
Eggs: X (humans: 22+X)
Sperm: X or Y (humans: 22+X or 22+Y)
What’s is commons in all sexually reproducing organisms regarding the amount of diploids and haploids?
Both have a diploid and haploid number
Define life cycle
Sequence of stages in the reproductive history of an organism from conception to its own reproduction
What alternates in sexual life cycles?
Fertilization and meiosis
Define fertilization
When a sperm cell (haploid) fuses with an egg (haploid) to form a zygote (diploid)
What is meiosis?
A process that creates haploid gamete cells in sexually reproducing diploid organisms
Meiosis is essential for sexual reproduction.
What is the result of meiosis in terms of chromosome number?
Daughter cells with half the number of chromosomes as the parent cell
This reduction is crucial for maintaining the species’ chromosome number through generations.
What is the diploid chromosome number in humans?
2n = 46
This means humans have 46 chromosomes in their somatic (body) cells.
What type of cells does meiosis produce?
Sperm and eggs that are haploid: n = 23
Haploid cells contain only one set of chromosomes.
How many rounds of division are involved in meiosis?
Two rounds of division
These rounds are referred to as Meiosis I and Meiosis II.
What is the significance of producing haploid gametes?
It allows for genetic diversity and maintains chromosome number upon fertilization
When two haploid gametes fuse during fertilization, they form a diploid zygote.
Fill in the blank: Meiosis produces _______ gamete cells.
haploid
Haploid cells are essential for sexual reproduction.
True or False: Meiosis results in daughter cells that are diploid.
False
Meiosis results in haploid daughter cells.
What type of cells does meiosis occur in?
Gametes (sperm/egg)
Meiosis is specifically involved in the formation of reproductive cells.
How many divisions occur during meiosis?
2 divisions
Meiosis consists of two rounds of cell division.
What is the result of meiosis in terms of daughter cells?
4 haploid daughter cells
Haploid cells contain half the number of chromosomes.
What type of cells does mitosis occur in?
Somatic cells
Mitosis is responsible for growth and repair in the non-reproductive cells.
How many divisions occur during mitosis?
1 division
Mitosis involves a single round of division to produce daughter cells.
What is the result of mitosis in terms of daughter cells?
2 diploid daughter cells
Diploid cells have a full set of chromosomes.
Are daughter cells genetically identical in mitosis?
Yes
Mitosis produces genetically identical daughter cells.
Are daughter cells genetically identical in meiosis?
No, they are genetically unique
Meiosis results in genetic variation among daughter cells.
What happens in prophase 1 of meiosis 1?
What happens in metaphase 1 and anaphase 1 of meiosis 1?
The image for anaphase is incorrect and the membrane should not be pinching in
What is telophase 1 and cytokinesis in meiosis 1?
Note in telophase the membrane starts pinching in
What’s happens in prophase 2 in meiosis 2?
What’s happens in metaphase 2 in meiosis 2?
What’s happens in anaphase 2 in meiosis 2?
Note the membrane DOES NOT start pinching yet
What’s happens in telophase 2 and cytokinesis in meiosis 2?
Note the membrane starts pinching in in telophase 2
What are the three ways Meiosis leads to genetic variation and how do they?
- Crossing over which produces recombinant chromosomes: they exchange genetic material
- Independent assortment of chromosomes where chromosomes are randomly oriented along the metaphase plate during metaphase 1. (Each can orient with either the maternal or paternal chromosomes closer to the given pole)
- Random fertilization: any sperm can fertilize the egg
What process ensures genetic diversity in sexually reproducing organisms?
Meiosis followed by fertilization
This process provides genetic variation that plays a role in natural selection.
What role does genetic variation play in evolution?
It plays a role in natural selection
Genetic variation allows populations to adapt to changing environments.
What drives the cellular process of meiosis?
The interaction of subcellular components and free energy
Free energy is required for the growth and reproduction of living systems.
Fill in the blank: _______ followed by fertilization ensures genetic diversity.
[Meiosis]
True or False: Meiosis is not essential for genetic variation in sexually reproducing organisms.
False
What is required for the growth and reproduction of living systems?
Free energy
Free energy is necessary for various cellular processes, including meiosis.
