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Praxis (7005) - Elem. Ed: Science > 2C2 Cell Division and Genetic Diversity > Flashcards

2C2 Cell Division and Genetic Diversity Flashcards

Learn about cellular reproduction, cell cycles, and the effects of mutations.

1
Q

What is gametogenesis?

A

The process of making sex cells, involving mitosis and meiosis to produce haploid daughter cells from a diploid parent cell.

Gametogenesis includes spermatogenesis in males and oogenesis in females.

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2
Q

Where are eggs made in female humans?

A

In the ovaries, while the female fetus is still developing.

The process begins with the formation of primary oocytes during fetal development.

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3
Q

When and where does spermatogenesis occur in male humans?

A
  • When: Continuously in the male reproductive system throughout a male’s life after puberty.
  • Where: In the Seminiferous tubules of the testes.

The process starts at puberty and involves the testes producing millions of sperm daily.

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4
Q

What are the stages of oogenesis?

A
  1. Pre-natal stage
  2. Antral stage
  3. Pre-ovulation stage

Oogenesis involves the maturation of oocytes, culminating in ovulation during the menstrual cycle.

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5
Q

What happens to primary oocytes during the pre-natal stage of oogenesis?

A

They arrest in the middle of meiosis I during the pre-natal stage.

This arrest occurs in prophase I and remains until puberty when hormonal changes resume their development.

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6
Q

What triggers the antral stage of oogenesis?

A

Puberty and the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH).

These hormones stimulate the growth of ovarian follicles, each containing an oocyte.

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7
Q

What is the fate of the polar body in oogenesis?

A

It will eventually degenerate and is not used for sexual reproduction.

Polar bodies are byproducts of meiosis that contain minimal cytoplasm and are not viable gametes.

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8
Q

When does the secondary oocyte complete meiosis II?

A

Only upon fertilization, becoming a true ovum.

Fertilization by a sperm triggers the completion of meiosis II and the formation of a zygote.

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9
Q

What are the main stages of spermatogenesis?

A
  1. Spermatocytogenesis
  2. Spermatidogenesis
  3. Spermiogenesis
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10
Q

How does mitosis differ from meiosis in terms of reproduction?

A
  • Mitosis is asexual reproduction producing identical diploid cells.
  • Meiosis is for sexual reproduction producing haploid gametes.
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11
Q

How does sexual reproduction differ from asexual reproduction?

A
  • Sexual reproduction: Involves two parents and genetic variation in offspring.
  • Asexual reproduction: Involves one parent and produces genetically identical offspring.

Sexual reproduction - e.g. human reproduction.

Asexual reproduction - e.g. yeast reproduction.

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12
Q

Give an example of a plant that reproduces asexually.

A

Strawberry plants shoot out runners along the soil that grow into new strawberry plants.

These are exact copies of the parent plant.

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13
Q

List one advantage and one disadvantage of asexual reproduction.

A
  • Advantage: Lots of offspring can be produced very quickly.
  • Disadvantage: Lack of genetic variation makes populations vulnerable to diseases.
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14
Q

List one advantage and one disadvantage of sexual reproduction.

A
  • Advantage: Fusion of two gametes increases genetic variation in offspring, enhancing survival.
  • Disadvantage: Takes time and energy to find mates.
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15
Q

What are the two main types of reproduction?

A
  1. Sexual
  2. Asexual
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16
Q

How do unicellular organisms like yeast reproduce?

A

Through mitosis, where one cell divides into two identical daughter cells.

This process is called budding in yeast, where a new cell grows out of the body of a parent cell.

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17
Q

What is mitosis?

A

The process where a cell duplicates its DNA and divides into two identical cells.

Mitosis consists of the following stages:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
5. Cytokinesis

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18
Q

What is meiosis?

A

The process of making sex cells (gametes) with half the DNA of the parent for sexual reproduction.

Meiosis consists of two divisions: meiosis I and meiosis II, resulting in four haploid cells.

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19
Q

What is vegetative propagation?

A

A type of asexual reproduction where new plants grow from runners, like in strawberries.

Other forms include grafting, layering, and the use of plant cuttings.

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20
Q

How do sea sponges reproduce asexually?

A

By budding, where a part of the organism pinches off and grows into a new individual.

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21
Q

What are gametes?

A

Sex cells, usually called eggs in females and sperm in males, involved in sexual reproduction.

Gametes are haploid, containing half the number of chromosomes compared to somatic cells.

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22
Q

What is the difference between haploid and diploid cells?

A
  • Haploid cells have half the genetic information (like gametes).
  • Diploid cells have a full set of DNA (like somatic cells).

Diploid cells have two sets of chromosomes, one from each parent, while haploid cells have one set.

23
Q

Is mitosis classified as asexual or sexual reproduction?

A

Asexual reproduction.

Mitosis produces cells that are genetically identical to the parent cell.

24
Q

What type of cells result from mitosis?

A

Diploid cells.

These cells are involved in growth, repair, and maintenance of tissues.

25
Q

Can mitosis lead to the creation of new organisms?

A

Yes, but it does not always.

In single-celled organisms like bacteria, mitosis (binary fission) results in new individuals.

26
Q

Which human body cells undergo mitosis?

A

Most human body cells, such as skin cells and taste buds.

Red blood cells are an exception, as they do not undergo mitosis.

27
Q

What is the primary purpose of meiosis?

A

To produce gametes for sexual reproduction.

28
Q

Why does meiosis involve halving the genetic material?

A

To bring it back to full at some point during fertilization.

This reduction is crucial for maintaining a stable chromosome number across generations.

29
Q

Is meiosis ever used for asexual reproduction?

A

No.

30
Q

What type of cells are produced by meiosis?

A

Haploid gametes.

These include sperm in males and eggs in females.

31
Q

What is an exception to the usual process of meiosis?

A

An ova can sometimes grow without being fertilized, having not gone through the correct stages of meiosis but still containing all necessary genetic information.

This process is called parthenogenesis, observed in some insects, reptiles, and fish.

32
Q

What is the chromosome number in daughter cells after mitosis?

A

Diploid (2n).

For humans, this means each daughter cell has 46 chromosomes.

33
Q

How many gametes are produced from one cell through meiosis?

A

Four.

For humans, this means each gamete has 23 chromosomes.

34
Q

How do the genetic contents of parent and daughter cells compare in mitosis?

A

Parent and daughter cells have identical diploid (2n) DNA in mitosis.

35
Q

Where can mitosis occur?

A

In any somatic cell that needs to replicate.

36
Q

Which organisms often use mitosis to reproduce quickly?

A

Many single-celled organisms.

e.g. bacteria and protozoa.

37
Q

Does asexual reproduction require fertilization or incubation?

A

No, it doesn’t require either.

Asexual reproduction can occur without the presence of another organism.

38
Q

What are some methods of asexual reproduction?

A
  1. Budding
  2. Fission
  3. Vegetative propagation

Each method varies by organism and environment.

39
Q

Why are populations of asexually created organisms vulnerable to environmental changes?

A

Due to their genetic uniformity.

A single change in the environment can affect all individuals equally.

40
Q

What are mutations?

A

DNA errors that result in changes to the genetic code, leading to population variation and influencing physical traits, behavior, and physiology.

Mutations can be spontaneous or induced by external factors like radiation.

41
Q

How do mutations contribute to evolution?

A

They create genetic variation, which is essential for evolution.

Variations that improve survival and reproduction are passed on, while those that hinder these processes are eliminated through natural selection.

42
Q

What is a somatic mutation?

A

Occur in non-reproductive cells and are usually not passed on to offspring. These can affect cell division and may lead to conditions like cancer.

Somatic mutations can accumulate over an organism’s lifetime.

43
Q

What is a germ-line mutation?

A

Occur in reproductive cells and can be passed on to offspring, affecting traits in future generations.

These mutations can influence the genetic makeup of populations over time.

44
Q

What are gene-level mutations?

A

Involve changes to short lengths of nucleotides. They can affect physical characteristics and play a significant role in evolution.

An example is insect resistance to pesticides.

45
Q

What are chromosomal mutations?

A

Involve changes to long lengths of nucleotides and often have severe consequences.

An example is Down syndrome, caused by an extra copy of chromosome 21.

46
Q

What causes mutations?

A
  • Spontaneous errors during DNA replication.
  • Exposure to mutagens like chemicals and UV radiation.

Mutagens can cause direct damage to the DNA structure.

47
Q

What is a substitution mutation?

A

A type of mutation where one codon is replaced by another, potentially altering the amino acid sequence of a protein.

Substitution mutations can be silent, missense, or nonsense.

48
Q

What is an insertion mutation?

A

Occurs when extra base pairs are added into the DNA sequence, which can disrupt the gene’s function.

Insertions can cause frameshift mutations, altering the entire downstream amino acid sequence.

49
Q

What is a deletion mutation?

A

It’s when a section of DNA is lost or removed, which can result in the loss of essential genetic information.

Deletions can also cause frameshift mutations, with significant impacts on protein function.

50
Q

How do variations caused by mutations affect a population?

A

These variations make individuals within a population unique, influencing traits like hair color, skin color, height, shape, and behavior.

These variations are crucial for natural selection and adaptation.

51
Q

Can mutations be beneficial?

A

Yes, if they result in traits that enhance an organism’s ability to survive and reproduce in its environment.

Beneficial mutations can spread through a population by natural selection.

52
Q

What role do codons play in mutations?

A
  • These are sets of three nucleotides that specify amino acids or signal the end of a protein.
  • Mutations in codons can alter protein synthesis and function.

The genetic code is redundant, meaning multiple codons can code for the same amino acid.

53
Q

What are mutagens?

A

These are environmental factors, such as chemicals and UV radiation, that can induce mutations in DNA.

Common mutagens include tobacco smoke, asbestos, and certain viruses.

Praxis (7005) - Elem. Ed: Science (36 decks)

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