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Biology > Genetics 1 > Flashcards

Genetics 1 Flashcards

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1
Q

DNA Purpose

A

The purpose of DNA is to store and transmit genetic information, serving as the blueprint for the structure and function of living organisms.

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2
Q

DNA Structure

A

DNA has a double-helix structure composed of two long strands made of nucleotides, which consist of a sugar-phosphate backbone and one of four nitrogenous bases (adenine, thymine, cytosine, or guanine).

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3
Q

DNA Replication

A

DNA replication occurs by the separation of the two DNA strands, followed by the synthesis of complementary strands using existing strands as templates, resulting in two identical DNA molecules.

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4
Q

Stages prior to mitosis

A

the cell must grow and replicate its chromosomes (DNA). Before cell division, each chromosome consists of identical ¨sister chromatids¨

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5
Q

Stages of mitosis ( PMAT )

A

Prophase: Long strands of DNA condense into chromosomes, Nucleus membrane dissolves

Metaphase: chromosomes line up in the middle of the cell ( they must be lined up for mitosis to continue )

Anaphase: Chromosomes split (now called sister chromatids) They then move to opposite sides of the cell

Telophase: The daughter chromosomes stretch out and become thinner until they are no longer visible, A new nuclear membrane forms around each group of daughter chromosomes, cell appears to have two nuclei

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6
Q

Results of Mitosis

A

In unicellular plants and animals mitosis results in an asexual offspring

In multicellular plants and animals it results in new growth (ex. healing wounds)

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7
Q

Meiosis I

A

Prophase I: Homologous chromosomes pair up (synapsis) and exchange genetic material (crossing-over).

Metaphase I: Paired homologous chromosomes align at the cell’s equator.

Anaphase I: Homologous chromosomes are pulled apart and move to opposite poles of the cell.

Telophase I: Two haploid daughter cells are formed, each with a mix of maternal and paternal chromosomes.

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8
Q

Meiosis II

A

Prophase II: A new spindle apparatus forms in each haploid daughter cell.

Metaphase II: Chromatids of each chromosome align at the cell’s equator.

Anaphase II: Sister chromatids are separated and move to opposite poles of the cell.

Telophase II: Four haploid daughter cells are produced, each with a unique combination of genetic material.

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9
Q

Results of Meiosis

A

The four haploid daughter cells can develop into gametes (sperm and egg cells) in sexual reproduction. Meiosis generates genetic diversity due to the processes of crossing over and the random assortment of chromosomes.

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10
Q

Compare Mitosis and Meiosis

A

Mitosis: Cells undergo mitosis for growth, repair, reproduction, and to maintain or replace damaged or old cells while ensuring genetic stability.

Meiosis: Cells undergo meiosis to produce gametes (sperm and egg cells) with half the usual number of chromosomes, ensuring genetic diversity in offspring during sexual reproduction.

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11
Q

Differences in meiosis and mitosis: number of divisions

A

Mitosis: One division.
Meiosis: Two divisions (meiosis I and meiosis II)

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12
Q

Differences in meiosis and mitosis: Daughter cells

A

Mitosis: Produces two diploid daughter cells (2n) with the same chromosome number as the parent cell.

Meiosis: Produces four haploid daughter cells (n), each with half the chromosome number of the parent cell.

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13
Q

Differences in meiosis and mitosis: Genetic Diversity:

A

Mitosis: Results in genetically identical daughter cells.

Meiosis: Generates genetic diversity through independent assortment and crossing over during meiosis I.

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14
Q

Differences in meiosis and mitosis: Occurrence:

A

Mitosis: Occurs in somatic (body) cells.

Meiosis: Occurs in germ cells (sperm and egg cells) for sexual reproduction.

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15
Q

Differences in meiosis and mitosis: Chromosomal Recombination:

A

Mitosis: No exchange of genetic material between homologous chromosomes.

Meiosis: Involves recombination (crossing over) between homologous chromosomes during meiosis I

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16
Q

Differences in meiosis and mitosis: Number of Rounds of DNA Replication:

A

Mitosis: One round of DNA replication.
Meiosis: One round of DNA replication before meiosis I, followed by another round before meiosis II.

17
Q

Differences in meiosis and mitosis: Chromosome Number in Daughter Cells:

A

Mitosis: Daughter cells have the same chromosome number as the parent cell.
Meiosis: Daughter cells have half the chromosome number of the parent cell.

18
Q

Differences in meiosis and mitosis: End Result:

A

Mitosis: Produces two genetically identical diploid cells.
Meiosis: Produces four genetically diverse haploid cells, which can fuse during fertilization to form a diploid zygote.

19
Q

Errors in Chromosome Structure

A

Errors can occur during the crossing over and when chemical bonds are re-formed.

20
Q

What is a Karyotype?

A

An organized picture of chromosomes
Arranged in order from largest to smallest
Sex chromosomes (X and Y) are last

21
Q

What characteristics are used to make a karyotype?

A

Size of the chromosome
Length of the arms of the chromosome
Position of the centromere
Banding patterns on the chromosome

22
Q

Why make a karyotype?

A

To determine if a person has an abnormal set of chromosomes. E.g…
Too many chromosomes
Too few chromosomes
Pieces of chromosomes missing
Extra pieces of chromosomes are present

23
Q

Common Errors in karyotyping

A

Monosomy - one member of a pair is missing
Trisomy - there is a set of 3 where there should be a pair
Additions - chromosomes have extra pieces attached
Deletions - parts of chromosomes are missing

24
Q

What is nondisjunction?

A

Nondisjunction is a genetic event during cell division, especially in meiosis.
It results in an abnormal number of chromosomes in daughter cells.

25
Q

Abnormalities that occur during nondisjunction

A

Types of abnormalities include aneuploidy (extra or missing chromosomes) and polyploidy (extra sets of chromosomes)

26
Q

Examples of abnormalities in nondisjunction

A

Aneuploidy can lead to genetic disorders and birth defects in humans.
Down syndrome is an example of a condition caused by trisomy resulting from nondisjunction.
Polyploidy is more commonly observed in plants and can increase genetic diversity.

Biology (13 decks)

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