3A - Cell Division and Genetics Flashcards
Interphase, Mitosis, and Meiosis.
1
Q
What is chromatin?
A
Loose, uncoiled DNA found in the nucleus when the cell is not dividing. It looks like spaghetti.
2
Q
What are chromosomes?
A
Tightly coiled DNA formed during cell division. They’re visible under a microscope and carry genetic information.
3
Q
What does double-stranded DNA mean?
A
DNA has two strands twisted into a double helix, like a twisted ladder. Each strand is a mirror of the other.
4
Q
What does single-stranded DNA mean?
A
One half of the DNA ladder — usually temporary, like during DNA copying or RNA formation.
5
Q
What is a centromere?
A
The center part of a chromosome where sister chromatids are stuck together. It’s what spindle fibers attach to during mitosis.
6
Q
What are homologous chromosomes?
A
A pair of chromosomes — one from mom, one from dad — that have the same genes, but maybe different versions (alleles).
7
Q
What are histones?
A
Proteins that DNA wraps around to stay organized. They help form chromatin.
8
Q
What is the cell cycle?
A
The full life of a cell: it grows, copies its DNA, divides, and starts over. It includes Interphase and Mitosis.
9
Q
What are the 3 parts of Interphase?
A
G1 (cell grows), S (DNA is copied), G2 (prepares to divide).
10
Q
What is the difference between somatic cells and gametes?
A
Somatic cells are body cells. Gametes are sex cells (sperm and egg).
11
Q
How many chromosomes do somatic cells have in humans?
A
46 chromosomes (23 pairs).
12
Q
How many chromosomes do gametes have in humans?
A
23 chromosomes. They’re haploid.
13
Q
What does diploid mean?
A
A cell with two sets of chromosomes (2n).
14
Q
What does haploid mean?
A
A cell with one set of chromosomes (n).
15
Q
What is DNA replication?
A
The process of copying DNA so each new cell gets a full set.
16
Q
What is a gene?
A
A section of DNA that gives instructions to make a protein. Genes determine traits like eye color or blood type.
17
Q
What is an allele?
A
A version of a gene. For example, one allele might give you brown eyes, another might give you blue eyes.
18
Q
What is the nucleus?
A
The control center of the cell. It holds the DNA and tells the cell what to do.
19
Q
What is the nucleolus?
A
A small part inside the nucleus where ribosomes are made.
20
Q
What are centrioles?
A
Tiny structures that help organize spindle fibers during cell division.
21
Q
What are spindle fibers?
A
Long strings that pull chromosomes apart during mitosis and meiosis.
22
Q
What is DNA?
A
Deoxyribonucleic acid — the molecule that holds genetic instructions for life.
23
Q
What is RNA?
A
Ribonucleic acid — helps carry out the instructions in DNA to build proteins.
24
Q
What does replication mean in biology?
A
Making a copy of DNA before the cell divides.
25
What is a mutation?
A change in the DNA sequence. It can be helpful, harmful, or have no effect.
26
What is the difference between mitosis and meiosis?
Mitosis makes 2 identical body cells. Meiosis makes 4 different gametes.
27
What does zygote mean?
The first cell made when a sperm and egg combine. It’s diploid and will divide to form a baby.
28
What is apoptosis?
Programmed cell death — the cell destroys itself on purpose if something’s wrong.
29
What is cancer in terms of cell division?
Uncontrolled cell division. The cell keeps dividing when it shouldn’t.
30
What are checkpoints in the cell cycle?
Control points where the cell checks itself before moving to the next phase. They help prevent mistakes.
31
What happens during Prophase in mitosis?
DNA coils into visible chromosomes made of two sister chromatids. The nuclear membrane breaks down, and spindle fibers start forming from centrioles.
32
What are sister chromatids?
Two identical copies of a chromosome, stuck together at the middle (called the centromere).
33
What happens during Metaphase?
Chromosomes line up in the middle of the cell (the metaphase plate). Spindle fibers attach to the centromeres.
34
Why is it important for chromosomes to line up during Metaphase?
So each new cell gets one full set of chromosomes when they’re pulled apart.
35
What happens during Anaphase?
The spindle fibers pull the sister chromatids apart, dragging each one to opposite sides of the cell.
36
What happens during Telophase?
Two new nuclei start to form. Chromosomes uncoil back into chromatin. Spindle fibers disappear.
37
What happens during Cytokinesis?
The whole cell splits into two. The cytoplasm divides, and two separate, identical cells are created.
38
What’s the difference between Telophase and Cytokinesis?
Telophase is when the nuclei form; Cytokinesis is when the cell itself splits.
39
What is meiosis?
Meiosis is the process that makes sex cells (gametes) like sperm and egg. It cuts the chromosome number in half.
40
How many cells are made at the end of meiosis?
4 non-identical haploid cells.
41
How many cell divisions happen in meiosis?
Two divisions: Meiosis I and Meiosis II.
42
What is the purpose of meiosis?
To create gametes with half the number of chromosomes (haploid) for sexual reproduction.
43
What happens in Prophase I of meiosis?
Homologous chromosomes pair up and crossing over happens.
44
What is crossing over?
When homologous chromosomes exchange pieces of DNA. It increases genetic variation.
45
What happens in Metaphase I of meiosis?
Homologous pairs line up in the middle of the cell.
46
What happens in Anaphase I?
Homologous chromosomes are pulled apart to opposite sides. Sister chromatids stay together.
47
What happens in Telophase I and Cytokinesis?
Two new cells form. Each has half the chromosomes (but still as sister chromatids).
48
What happens in Meiosis II?
The two cells from Meiosis I divide again, just like mitosis.
49
What happens in Prophase II?
Spindle fibers form again in both cells.
50
What happens in Metaphase II?
Chromosomes line up in the middle of each cell.
51
What happens in Anaphase II?
Sister chromatids are pulled apart to opposite sides.
52
What happens in Telophase II and Cytokinesis?
4 haploid cells are made. Each is genetically unique.
53
What are gametes?
Sex cells — sperm in males, eggs in females. They are haploid.
54
What does haploid mean?
A cell with half the usual number of chromosomes (n).
55
What does diploid mean?
A cell with the full set of chromosomes (2n).
56
What are homologous chromosomes?
Chromosome pairs — one from mom, one from dad — with the same genes.
They are similair but not identical/
57
How is meiosis different from mitosis?
Meiosis makes 4 unique gametes with half the DNA; mitosis makes 2 identical body cells.
58
What is independent assortment?
A thing that happens in metaphase 1 of meiosis.
Independent assortment is when genes for different traits can be passed down separately from each other when gametes (sperm or eggs) are made. Genes for different traits are inherited independently of each other, thanks to how chromosomes line up with each other during meiosis
59
What is independent assortment?
A thing that happens in metaphase 1 of meiosis.
Independent assortment is when genes for different traits can be passed down separately from each other when gametes (sperm or eggs) are made. Genes for different traits are inherited independently of each other, thanks to how chromosomes line up with each other during meiosis
Imagine youre picking an outfit
- you choose a shirt and pants.
- the shirt you chose doesnt affect your pants
In bio its like this:
- Just becauase you inherit your dads eye colour, dont mean youll also inherit his eye colour.
- no causation
- The gene for your eye colour is sorted independently from the gene for your hair colour in reproduction.
60
crossing over/ synapsis
Crossing over is when two chromosomes swap pieces of DNA.
It happens in Prophase I of meiosis.
The chromosomes line up and trade parts, like swapping cards.
This makes new mixes of genes and adds genetic variety.
That’s one reason why siblings can look different.
61
What are autosomes?
Autosomes are chromosomes that carry genes for everything except sex.
Humans have 44 autosomes (22 pairs).
They control traits like eye color, height, and blood type.
They are different from the sex chromosomes (X and Y).
62
What is a karyotype?
A karyotype is a picture of all the chromosomes in a cell, lined up in pairs.
It shows if there are the right number of chromosomes and checks for problems.
Humans should have 46 chromosomes (44 autosomes and 2 sex chromosomes).
It’s used to find genetic disorders or see if someone is XX or XY.
Think of it like a class photo of your chromosomes.
63
What is Down syndrome?
Down syndrome is a genetic condition where a person has 3 copies of chromosome 21 (called trisomy 21).
This happens because of a mistake in cell division during the formation of sperm or egg cells.
It can cause physical traits (like a flat face and small ears), learning delays, and sometimes health problems.
It’s caused by having one extra chromosome.
64
What is Turner’s syndrome and how does it happen?
Turner’s syndrome is a genetic condition where a female has only one X chromosome (XO instead of XX).
It happens because of a nondisjunction mistake during meiosis, where one sex cell ends up with no sex chromosome.
When that joins with a normal X, the result is XO.
This can cause short height, delayed puberty, infertility, and some physical differences.
65
What is Klinefelter’s syndrome and how does it happen?
Klinefelter’s syndrome is when a male has an extra X chromosome — so instead of XY, he has XXY.
It happens because of nondisjunction during meiosis (the chromosomes don’t split properly).
It can cause taller height, less body hair, wider hips, and infertility.
Some may have mild learning or language delays.
66
What is Jacob’s syndrome and how does it happen?
Jacob’s syndrome (XYY) is when a male has an extra Y chromosome, so instead of XY, he is XYY.
It happens because of a meiosis mistake where a sperm gets two Y chromosomes.
Boys with XYY are usually taller, may have mild learning or speech delays, and might have some behaviour challenges, but most live normal lives and are fertile.
67
What is Triple X syndrome and how does it happen?
Triple X syndrome is when a female has three X chromosomes instead of two — so she is XXX.
It happens because of nondisjunction during meiosis, where an egg or sperm ends up with an extra X.
Girls with XXX are usually taller, may have mild learning or speech delays, and most live normal, healthy lives and are fertile.
68
What is binary fission?
Binary fission is how bacteria and other single-celled organisms reproduce.
The cell copies its DNA and then splits in two, making two identical cells.
It’s a type of asexual reproduction — no partner needed
69
What is bacterial conjugation?
Conjugation is when one bacterium passes DNA to another using a tube called a pilus.
It doesn’t make new cells — it just shares genes, like antibiotic resistance.
It helps bacteria adapt and survive, but it’s not reproduction.
70
What is budding?
Budding is a type of asexual reproduction where a new organism grows off the side of the parent.
The bud is a genetic copy and may break off or stay attached.
It happens in things like yeast, hydra, and some sponges.
71
What are spores?
Spores are tiny, tough asexual reproductive cells made by fungi, some plants, and bacteria.
They can survive harsh conditions and grow into new organisms when the environment is right.
They help with spreading and survival.
72
73
Alternation of Generations
A life cycle found in plants, algae, and some fungi where two distinct generations alternate: one haploid (n) and one diploid (2n).
74
Haploid Generation (Gametophyte)
The generation that has one set of chromosomes (n) and produces gametes (sperm and egg).
75
Diploid Generation (Sporophyte)
The generation that has two sets of chromosomes (2n) and produces haploid spores by meiosis.
76
Sporophyte
The diploid generation (2n) in alternation of generations, which produces spores through meiosis.
77
Gametophyte
The haploid generation (n) in alternation of generations, which produces gametes (sperm and egg).
78
Fertilization
The fusion of two gametes (sperm and egg), forming a diploid zygote, which grows into the sporophyte.
79
Spore
A haploid cell produced by meiosis in the sporophyte generation that can grow into a gametophyte.
80
Gametes
Haploid reproductive cells (sperm and egg) produced by the gametophyte generation.
81
Zygote
A diploid cell formed when a sperm and egg combine during fertilization, which grows into a sporophyte.
82
Genetic Diversity
The variation in the genetic makeup of individuals in a population, which is increased through meiosis and fertilization.
83
Fern Life Cycle (Alternation of Generations) 🌱🔄
Sporophyte (2n) → Produces spores in sporangia (through meiosis).
Spores (n) → Land and grow into a gametophyte (n).
Gametophyte (n) → Produces gametes (sperm & eggs) through mitosis.
Fertilization → Sperm (n) fertilizes egg (n) → Forms zygote (2n).
Zygote (2n) → Grows into a new sporophyte (2n) through mitosis.
Cycle repeats: New sporophyte begins the cycle again! 🌿🔁
84
"Spores Get Fertilized, Grow Ferns." 🌀
Spores (start the process)
Gametophyte (grows from spores)
Fertilize (sperm + egg = zygote)
Grow (zygote grows into fern)
Fern (the adult plant you see!)
