Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

OCR AS-level Biology > 2.1.6 cell division, cell diversity & cellular organisation > Flashcards

2.1.6 cell division, cell diversity & cellular organisation Flashcards

(71 cards)

Start Studying
1
Q

What are the differences between chromosomes and chromatids

A

chromosomes have no centromeres

Chromatids have a centromere and are identical sisters. they are like two chromosomes together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

state what the cell cycle is an outline the names of its stages

A

The cell cycle is the regulated cycle of division with intermediate growth periods

Interface, mitosis/meiosis, cytokinesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

outline what happens during interphase

A

G1: Cell synthesises proteins + organelles for replication e.g.tubulin for spindle fibres and cell size doubles

S: DNA replicates = chromosomes consist of two sister chromatids joined at a centromere.

G2: organelles divide. This is where the cell grows, energy stores are increased, and duplication errors are looked for

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the purpose of mitosis

A

produces to genetically identical daughter cells for growth, cell replacement/tissue repair and asexual reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Name the stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Outline what happens during prophase

A

chromosomes condense and super coil (become visible)

The nucleolus disappears and the nuclear membrane breaks down so chromosomes are free in the cytoplasm

The centrioles migrate to the poles and spindle fibres form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Outline what happens during metaphase

A

centrioles release spindle fibres which attach to chromosomes

Chromosomes align along the equator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Outline what happens during anaphase

A

spindle fibres contract (centromeres divide)

this separates the sister chromatids of the chromosomes. and The chromosomes are then pulled to the poles of the cell

spindle fibres break down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Outline what happens during telophase

A

nuclear envelope reforms around chromosomes

chromosomes will decondense (becoming invisible again)

cytokinesis occurs

two genetically identical daughter cells have been performed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is the cell cycle regulated

A

checkpoints regulated by cell signalling proteins ensure damaged cells do not progress to next stage of cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe what happens at each key checkpoint in the cell cycle

A

G1 checkpoint: checks to see if DNA is damaged

G2 checkpoint: checks to see if DNA is replicated properly

prophase checkpoint: Spindle assembly checkpoint, checks for alignment of chromosomes

apoptosis: programmed cell death, if any checks fail then it goes to G0

G0= cell leave cycle To differentiate. DNA damaged, cel arrest, old cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is meiosis

A

A form of cell division that produces for genetically different haploid cells (cells with half the number of chromosomes found in the parent cell) Known as gametes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe what happens during prophase I

A

chromosomes condense and they form homologous pairs by synapsis forming a bivalent

crossing over occurs between nonsister chromatids

nuclear envelope and nucleolus disappear and break down

centrioles move to the poles of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe what happens during meta phase 1

A

spindle fibres from centrioles , Attach to the chromosomes at the centromere

The homologous pairs lineup along the equator by independent assortment (chromosome arrangement along the equator is random)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe what happens during anaphase 1

A

Chromosomes are pulled to the poles by spindle fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe what happens during telophase I

A

Nuclear envelope reforms, cytokinesis occurs, two cells are formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe what happens during prophase II

A

nuclear envelope breaks down

nucleolus disappears

centrioles migrate to the polls at 90° to prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe what happens during metaphase II

A

spindle fibres attach to chromosomes and align along equator

Independent assortment of chromatids occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe what happens during anaphase II

A

Spindle fibres pull chromatids to poles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe what happens during telophase II

A

nuclear envelope reforms
nucleolus reforms
chromosomes unravel

cytokinesis occurs
For genetically non-identical daughter cells are made

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Define haploid

A

Single set of unpaired chromosomes, half the genetic information e.g. egg and sperm (gametes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Define diploid

A

Containing two complete sets of chromosomes, one from each parent. full set of genetic information

normal body cells have the normal number of chromosomes = 46 (2n). We call these deployed, it means that each body cell contains two of each chromosome is one from mum and one from dad

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Define homologous pairs

A

A homologous chromosome is a set of one maternal chromosome and one paternal chromosomes that pair up with each other inside a cell during meiosis

. A homologous pair is a pair of chromosomes which have the same genes but different alleles

Gammys have half the normal number of chromosomes = 23 (n)

There is only one copy of each chromosome and at fertilisation a haploid sperm or fuse with a haploid egg which makes a cell with a normal diploid number of chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Define bivalent

A

A pair of homologous chromosomes. During meiosis prophase I . When they stick together they cross over and share genetic information

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Define crossing over
The exchange of genetic material between homologous chromosomes
26
Define independent assortment
formation of random combinations of chromosomes along the equator in meiosis = variation
27
Define alleles
Different form of the same gene
28
define synapsis
The side-by-side pairing of homologous maternal and paternal chromosomes at the start of meiosis ie. how they stick together
29
How does meiosis produces genetic variation
crossing over during meiosis I Independent assortment of analogous chromosomes and sister chromatids results in new combinations of alleles
30
Which part of meiosis is what causes diploid cells to become haploid cells (2n to become n)
meiosis II
31
How do cells become specialised
Some genes are expressed while others are silenced due to cell differentiation mediated by transcription factors. Cells produce proteins that determine their structure and function
32
What is a stem cell
on differentiated cells that can divide indefinitely and turn into other specific cell types
33
Name the two broad categories of stem cells
embryonic stem cells: the stem cells divide and differentiate into specialised embryonic tissues adult stem cells: the stem cells are involved in repair and replacement of specialised cells eg blood, skin
34
What must all stem cells be able to do
divide repeatedly Differentiate into specialised cell types i.e. potency
35
Name and to find the four types of stem cells
totipotent: can develop into any cell type including the placenta and embryo pluripotent: can develop into any cell type excluding the placenta and embryo. They are capable of producing all cells drive from a particular German later e.g. ectodermal, endoderm Multipotent: can only develop into a few different types of cells Unipotent: can only develop into one cell type e.g. muscles stem cells
36
Suggest some uses of stem cells
repair of damaged tissues drug testing on artificially brown tissues treating neurological diseases e.g. Alzheimer’s Researching developmental biology e.g. formation of organs
37
Describe embryonic stem cells
as the name implies they are taken from the embryo. In very early stages they are totipotent and from the in a mass of a blastocyst they are pluripotent. Developments suggest that these could be used for treatment of a variety of conditions e.g. Parkinson’s and growing new tissues. Their use is controversial and research tightly regulated
38
Describe Adult stem cells
these have the ability to divide And differentiate. Generally they are multipotent and are usually referred to by where they are found. They have been successfully used to treat leukaemia
39
once differentiated what do cells lose
their ability to divide and totipotency eg they lose the ability to do everything
40
What are cells that can differentiate called in animals
animals: stem cells plants: Meristematic cells
41
describe the structure of erythrocytes (red blood cells) and how this relates to their function
Very small, so have a large surface area to volume ratio. This means oxygen can diffuse across the membranes and easily reach all regions inside the cell biconcave shape: increases surface area to volume ratio flexible: well developed cytoskeleton enables them to change shape so they can twist and turn to travel through narrow arteries No nucleus: more space for haemoglobin
42
What is the general function and location of red blood cells
They carry oxygen from the lungs to respiring cells and located in the bloodstream
43
what is the structure of white blood cells and how does this relate to their function (neutrophils)
twice the size of RBC Each white blood cell contains a multilobed nucleus: which provides flexibility to engulf pathogens lots of mitochondria: to carry out aerobic respiration to produce ATP which provides a lot of energy to carry out phagocytosis lots of lysosomes: provides lots of digestive enzymes to breakdown the engulfed particles
44
What is the general function and location of white blood cells
They are located in the bloodstream after being produced in the bone marrow. They ingest bacteria and some fungi via phagocytosis and engulf pathogens.
45
Describe the structure of sperm cells and how this relates to their function
they have lots of mitochondria: to carry out aerobic respiration to produce ATP they are very small, long and thin: facilitates for easy movement Acrosome: releases enzymes when sperm cell reaches the ovum. enzyme dissolves out of protective covering of the ovum allowing sperm head to enter Head: contains haploid mail gamete nucleus and Acrosome Tail: the energy provided by the mitochondria provides energy for the tail to move to propel the tail towards the ovum Nucleus: haploid mail gamete nucleus containing DNA of cell Receptors: has special receptors which enable cell to bind with an egg
46
What is the general function of a sperm cell and where is it located
Located in the testicles of a male. It’s general function is to reach the ovum to penetrate and fertilise the female egg to produce new offspring
47
Describe the structure of epithelial cells and relate this to the function
Squamous epithelium cells: smooth, flat, very thin, fit closely together - to produce smooth, low friction surface where fluids can move easily Ciliated epithelial cells have cilia-move in synchronised wave to move particles away
48
What is the general function and location of epithelial cells
located lining e.g. organs, blood vessels and make up tissues Which cover surfaces
49
what is the structure of a Palisade cell and relate it to its function
Long and cylindrical: pack closely together with a bit of space between them for air to circulate, carbon dioxide diffuses into the cell and these air spaces Large vacuole: chloroplast other for pointed nearer to the so, reducing diffusion distance for carbon dioxide lots of chloroplasts: which carry out photosynthesis Cytoskeleton threads: move the chloroplasts nearer to the upper surface of the leaf when sun light intensity is low, but further down when it’s high
50
What is the general function and location of palisade cells
Located within leaves, enable photosynthesis to be carried out efficiently
51
Describe the structure of guard cells and how this relates to the function
contain chloroplasts: site of photosynthesis Surround is stomata: open and close tomato to allow for gassiest exchange required for photosynthesis cell can become turgid: when turgid, outer walls stretch causing guard cell to bulge and form a pore (stomata) between them allowing gaseous exchange
52
What is the general function and location of the guard cells
Located in Leaf epidermis, control the opening and closing of the stomata
53
What is the structure of a root hair cell and How does this relate to its function
they have hair like projections: which greatly increases surface area for absorption of water and mineral ions eg nitrates from soil Mitochondria: produce ATP to actively transport mineral ions into root hair cell Large vacuole: maintain shape
54
What is the general function and location of root hair cells
Located in epidermal cells of the outer layer of young plant roots. They absorb water and mineral ions from the soil
55
What is the structure of epithelial tissue and related to its function
No blood vessels: sells receive nutrients by diffusion from tissue fluid in underlying connective tissue squamous epithelial tissue : Single layer of fat cells: line the surface e.g. alveoli in the lungs providing a short diffusion pathway ciliated Epithelial tissue: layer of column shaped cells: covered in Celia, work to move mucus which has small particles and micro organisms trapped
56
What is the general function of epithelial tissue and where is it located
Located widespread throughout the body and forms a covering of a body services and other major tissue in glands
57
Describe the structure of cartilage and how it relates to its function
Cartilage is a type of Smoove, elastic tissue that provides structural support to the body. It provides a framework, helps provide flexibility
58
What is the general function of cartilage and where is it located
Located at various points within the body at joints between bones and is connective tissue
59
ppq: Name the type of nuclear division that occurs in plant growth
Mitosis
60
ppq: Name a location where growth occurs in a plant
Meristem
61
ppq: the stages of meiosis in which the following events occur ``` independent assortment formation of the spindle apparatus separation of sister chromatids formation of nuclear membranes Chromosomes pulled to opposite poles ```
independent assortment = metaphase I and metaphase II formation of the spindle apparatus= prophase I separation of sister chromatids= Anaphase II formation of nuclear membranes = telophase II Chromosomes pulled to opposite poles= anaphase I
62
ppq: Explain why meiosis needs to have twice as many stages as mitosis
To half the chromosome number e.g. reduce from 2N to N also to separate On monikers pairs of chromosomes because DNA has been previously replicated and chromosomes are two chromatids at the start
63
ppq: Before the division of the nucleus of a cell the genetic material must replicate explain why this is essential
cells are genetically identical so both daughter cells receive a full copy Daughter cells have all the identical genetic material
64
ppq: Explain what is meant by a homologous pairs of chromosomes
One maternal and one paternal, Carrie same jeans and are genetically identical They have a central man in the same position and are of the same shape and size
65
ppq: State what is meant by the term tissue
A group of cells specialised to perform A specific function
66
ppq: Describe the function of squamous and ciliated tissue and a specific location in the human body
squamous: acts as a surface and is found in the alveoli Ciliated: moves mucus and is found in the trachea
67
ppq: complete the following paragraph cells that are not specialised but still have the ability to divide are called ___ cells. such cells can be found in the ____ of the long bones of mammals. The cells can ____ into other types of cell, such as red blood cells that carry oxygen in the blood. In plants ____ Tissue also contain cells that are not specialised
cells that are not specialised but still have the ability to divide are called STEM cells. such cells can be found in the BONE MARROW of the long bones of mammals. The cells can DIFFERENTIATE into other types of cell, such as red blood cells that carry oxygen in the blood. In plants MERISTEM Tissue also contain cells that are not specialised
68
ppq: In more advanced organisms, cells are organised into tissues consisting of one or more types of specialised cells. Describe how cells are organised into tissues, using xylem and phloem as examples
xylem: consists of vessels and one example of its specialisation is that its walls are lignified, has no end walls and is waterproof. and it moves water phloem: has sieve tube elements and companion cells and one example of cell specialisation is that it has no nucleus and many plasmodesmata. it is where translocation occurs
69
ppq: Name two parts of a plant where meristematic tissue can be found
Root and shoot
70
ppq: State one way in which the product of meiosis are different from the products of nuclear division in meristematic tissue
In meiosis cells produced are not genetically identical
71
ppq: During interphase the genetic material is copied, state to other processes that occur during interphase
Protein synthesis occurs, cell growth and ATP production

OCR AS-level Biology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions